Senna was supposed to be Lucian's counterpart. Senna would provide Lucian with heals and shields while Lucian was dealing all of the damage. However, since her release, Senna has been taking the spotlight away from Lucian and putting it on herself. Her damage and abilities seem to outshine Lucian all together. She is supposed to be a Support Marksman, but she is taking the role of a traditional Marksman which makes her so controversial. Nerf after nerf, Senna still continues to be a good pick as ADC when she is paired with a tanky or mage Support. You may be wondering "why would anyone pick her as an ADC?". That question is valid, but you have to understand her abilities and mechanics to be able to answer this.

Senna, The Redeemer

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Passive

Weakened Soul: Senna's basic attacks and abilities apply Mist for a short time. Hitting them again with basics or abilities will allow Senna to collect the Mist (soul) from the enemy dealing a percent of their current health.

Absolution: The Mist that Senna collects from her enemies stack and give her stats throughout the game. Another way Senna collects Mist is through the death of other units. Every time a unit of any kind dies near Senna, a soul will pop out of the killed unit. Senna can then attack it, set it free, and then absorb it. However, through the patches, they nerfed Senna's soul drop rate to 22% on lesser minions and monsters she does not kill but large minion and monsters are guaranteed to drop souls. With each soul she collects, Senna gains .75 AD and 3 Gold. When she hits increments of 20 with her soul stacks, "Absolution" grants Senna 25 bonus range and 15% critical strike chance. When Senna reaches 100% critical strike chance, she will convert 35% of the excess critical strike chance into life steal. Senna starts out with 600 attack range which is shy of Caitlyn's 650 attack range, but you can see how Senna can easily surpass that.

Relic Cannon: Senna's basic attacks deal 20% bonus physical damage on-hit and give her 10 - 20% of her target's movement speed as bonus movement speed for a short duration.

Abilities

Q: Piercing Darkness

Senna fires a laser in a line in the direction of her enemy. This heals her and allies, but deals physical damage to any enemies caught in the line. This can apply Mist or collect the Mist that already has been applied to her enemies. Auto attacking reduces its cooldown.

W: Last Embrace

Senna throws out an orb in a straight line that collides with the first enemy hit. The first enemy hit is damaged and then roots any surrounding enemies in the immediate area after a short duration. If the root kills a target, the effects are triggered immediately. This can also apply Mist or collect Mist.

E: Curse of the Black Mist

Senna turns into a wraith providing camouflage for her and her teammates. Enemies cannot see inside the mist unless they are standing inside of it. Therefore, the team completely disappears. Once teammates exit the mist, they become untargetable for a short delay or until they attack. Senna also provides her team with movement speed allowing them to run down enemies or run to safety.

R: Dawning Shadow

Senna fires a huge blast of light that shields herself and allies caught in the blast, but damages enemies caught in the middle. This can be shot cross-map which can turn the tide of a fight in another lane. This can apply Mist or collect Mist.

Soul Eater/Fasting Senna

Senna's passive abilities alone make her such a strong champion. She is meant to poke down her enemies with her long range, while keeping her team healthy and safe with her heals, shields, and camouflage. Poking her enemies down grants her the Mist stacks allowing her to never endingly boost her damage, range, critical strike chance, and life steal. Now instead of being used for pure utility and support, we put her into the main damage role. Someone picking Senna would play her as ADC, except the kicker is that you would try your best not to farm the minions. The whole point of this farming technique is to play an oppressive, yet safe, lane. Senna has all the time in the world to harass the enemy bottom lane every time they step up to farm a minion.

It is up to the enemy laners to decide to risk getting farm and taking damage or letting it die which means they lose gold. You would think playing an overly aggressive lane would result in being ganked, but Senna's kit is full of survivability that it is hard to execute a gank successfully. While Senna is harassing, the Support is farming the minions. The Support gets a lot of gold themselves allowing them to buy items to make them more tanky or do more damage. This essentially gives you two carries, depending on if you want a tanky support or mage support. How does Senna get her gold? Individual souls only give her 3 gold. That is correct, but since Senna first buys the item Spectral Sickle she gets gold from its passive.

First Item: Spectral Sickle

Spectral Sickle's unique passive is Tribute. When Senna is near an ally, any damage she does while harassing her enemies generates gold for her. Senna's whole point in lane is to harass with her abilities and attack range that she will be generating enough gold to replace not farming minions. We do not want the minions to go to waste, so it is the Supports job to farm those minions while Senna harasses. Harassing makes it difficult for your counterparts to farm and get gold for themselves. This gives your lane a gold lead just by oppressing the enemy laners. Not to mention Senna will passively generate 2 gold per 10 seconds because of the stats from the Spectral Sickle. She is a walking bank.

The Tribute passive goes for another cycle when Spectral Sickle transforms into Harrowing Crescent. Senna still needs to damage enemy champions to generate money for herself and she gets an increase of 3 gold per 10 seconds. She also gets the unique active of Warding which allows her to place 3 wards from her item. With the 3 extra wards she is granted, she is able to provide the same vision her Support would.

When Harrowing Crescent transforms into the Black Mist Scythe, the tribute passive disappears. At this point, you would think Senna would have to kill minions to get gold which is the opposite of what she is supposed to do. However, the Black Mist Scythe has a passive that makes you receive diminished gold from excess minion kills. To solve this issue and still get the right amount of gold you deserve, Senna has to farm equal to or less than 20 minions every 5 minutes. You can also farm your Junglers camps if they allow you to as they count as monsters not minions.

Second Item: Boots of Swiftness

Boots of Swiftness are the best boots that you could get for Senna. They provide a flat movement speed of 60 and reduce the effects of movement slowing effects by 25%. Since Senna is an immobile champion, that movement slow reduction goes a long way. The flat movement speed these boots provide are more than any other pair of boots. You can say that Mobility Boots provide the most movement speed, but that is only temporary and it that massive movement speed boost only triggers out of combat. Boots of Swiftness are more consistent.

Not to mention, they do very well with Senna's Relic Cannon passive that gives her a percent of her target's movement speed. The rune Approach Velocity also pairs well with these boots because they provide a 15% movement speed increase when you impair an enemy champions movement. You impair enemy champion movements with the keystone Glacial Augment. If you choose the rune Magical Footwear, then you will be granted an additional 10 movement speed on top of the flat 60. We will touch on runes later!

Third Item: Umbral Glaive

The Umbral Glaive is a great official damage item for Senna to purchase. The stats the Umbral Glaive provides synergizes well with Senna's abilities. Her Piercing Darkness, Last Embrace, and Dawning Shadow all scale with AD. The 10% Cooldown Reduction lets her use her abilities more frequently. The 12 Lethality allows her abilities and basic attacks to ignore 12 armor on her target. So if her target had 25 armor and Senna hit the target with her ability, that ability would hit as if the target only had 13 armor. ADCs do not normally build armor, so this is especially deadly towards them.

Senna's abilities and basic attacks out-range the enemy ADCs most of the time, so she is able to hit them hard. In teamfights, her Piercing Darkness and Dawning Shadow go through multiple champions and can find their way to the enemy ADC in the backline. They can either be knocked out of the fight and forced to back off or be an easy target to finish off. One of the more important stat that is provided is the Blackout passive. The Blackout passive allows you to one shot wards to deny enemy vision and Senna has a slow attack speed so this works well with her. The ability to deny enemy vision and place a ton of your own vision is what makes this item so valuable.

Fourth Item: Duskblade of Draktharr

This item provides Senna with a great burst of damage. The 60 AD scales well with her Q, W, and R. Again, the 10% Cooldown Reduction allows her to use her abilities more often. The 21 Lethality allows you to ignore an additional 21 armor. At this point you would have 33 Lethality. This is important because most ADCs have a base armor range of 20 - 30 armor that grows slowly with each level up. You would be hitting them as if they had around 0 or near zero armor. If you are able to stay ahead of your enemy ADC, your lethality will scale up with your level and the armor growth on your enemy does not play a factor unless they put a halt on their build to build armor items.

This would make them deal less damage in teamfights, but be tankier. Less damage is not good for the ADC as their job is to have the most DPS in fights. The Nightstalker passive from this item synergizes well with Senna because all you have to do to become unseen and get the bonus physical damage is to use Curse of the Black Mist. Remember, this camouflages you and counts as being unseen. Landing a great Q or R will deal bonus damage to the backline.

Fifth Item: Edge of Night

Edge of Night is more of survivability item that still fits into Senna's desired build path. Everyone could use some extra health and the extra 325 is great in allowing you to take a little bit more extra damage. The 55 AD again stacks well with Q, W, and R. The 10 Lethality helps ignore even more armor. The Spell Shield passive is what makes this item so valuable to Senna. Being an immobile champion, she has no way to avoid being engaged on by Pantheon W or Morgan Q. The Spell Shield allows Senna to eat one enemy ability and remain safe. That one ability is the difference between life or death. After being triggered, it will refresh in 40 seconds if no damage has been taken from champions. Since Senna usually positions in the backline, she is relatively safe and can refresh this shield with ease. Everyone is not perfect so having this is as a safe guard is paramount.

Sixth Item: Rapid Firecannon

Rapid Firecannon is the last item that Senna will build. The 30% Attack Speed is not a huge deal because Senna's Attack Speed Ratio is very low so it has little affect on how fast she attacks. The 25% Critical Strike Chance is a good stat Senna gains because critical striking with a basic attack makes it do increased damage. However, the more important detail about this stat is that it can count towards excess Critical Strike Chance that can be converted into Lifesteal. This is assuming you have been gathering souls well and have reached near 100% Critical Strike Chance. The extra Lifesteal allows Senna to stay up longer in fights to provide heals for the team and be able to heal herself more often. The 5% movement speed goes well with her Relic Cannon passive, Approach Velocity Rune, and Boots of Swiftness.

The Energized passive stacks as you move and attack. Once you have become Energized, the Sharpshooter passive becomes active. This grants you 120 bonus magic damage on your attacks, but most importantly you are granted increased range. If you have been collecting souls well on Senna you would already have an impressive attack range, but adding 35% bonus range to your current range would allow you to hit targets from crazy distances. The other neat thing is that Senna's Piercing Darkness scales with her attack range. For example, having 750 attack range for your basic attacks also allows your Piercing Darkness to have the same range. You can easily hit the enemy backline and keep teammates healed from a safer distance.

Runes: Inspiration + Precision

Glacial Augment is the keystone you run for this. Glacial Augment allows your first attack on enemy champions to slow them for a short time. When enemies are slowed by Senna's attack, Senna's Relic Cannon passive gives her that bonus movement speed so that she may run them down with ease. On top of that, her attack will apply Mist because of the Weakened Soul passive. When Senna gets into range, she can pull the Mist out of her enemies dealing damage equal to a percent of their current health and gives her a soul stack. All in all, this keystone allows Senna to close the gap quickly so that she can deal more damage and get her stacks.

Magical Footwear allows you to receive a free pair of Slightly Magical Boots that provide 25 movement speed and a bonus 10 movement speed. You receive these boots after 12 minutes unless you get takedowns which decreases this time. You already get bonus movement speed from Curse of the Black Mist that will allow you to get back to lane faster, chase someone down, or run away. Plus, the Relic Cannon passive gives you movement speed. This rune saves you the gold and allows you to put it into items instead.

Biscuit Delivery is a rune that you take to improve your sustainability. You get a biscuit every 2 minutes until 6 minutes and it they give you 10% of your missing health and mana. A bonus is that they also give you 50 more mana when you sell them or consume them. More mana and more health allows Senna to stay in lane longer and outlast her opponents. This forces them to take a bad recall or stay in the lane and get punished.

Approach Velocity is a rune I briefly touched on earlier. This one gives you the bonus movement speed for impairing an enemy champions movement or if your ally has their movement impaired. Glacial Augment counts as impairment and this counts towards the bonus movement speed. Not to mention you have the Relic Cannon passive that gives you a percent of your target's movement speed. The runes and passives working in unison give Senna a large burst of movement speed so that she is able to close the gap and finish her combos that result in massive damage.

Traditionally, Senna would build Manamune because she is very mana heavy. Presence of mind allows her to ignore that item because every takedown restores 20% of her maximum mana. Additionally, it provides an increase of her maximum mana by 100. This stacks up to 5 times for a total of 500 mana. This rune ensures that Senna does not have to worry about running through her mana as often.

Either Cut Down or Coup De Grace are the last runes you would lock in. It is very match up dependent. If you are laying versus a couple tanks, it would be optimal to take Cut Down because you would deal more damage to people with more health than you. Plus, the percent of current health damage from the Weakened Soul passive will scale with this rune well. If the team is more on the squishy side or does not have many tanks, you should take Coup De Grace. Coup De Grace lets you deal 8% more damage to enemies below 40% health. This also scales well with the Weakened Soul passive.

The rune shards are up for your choosing but double adaptive force gives you extra damage and armor works best because ADC role traditionally deals physical damage. In Slot 1, Attack speed shard does not scale well and the cooldown reduction is not needed because you get all cooldown reduction from your items. In Slot 2, extra damage is more valuable then extra defensive stats. In Slot 3, bonus health is not needed because your items give you a good bit of health. However, you can choose between armor shard or magic resistance shard depending on your match up.

Synergies

Tahm Kench, The River King

Everyone is annoyed with how tanky Tahm Kench is and how safe he is able to keep his laner. That is exactly what Fasting Senna wants to abuse. Tahm Kench brings more survivability into the lane with his W: Devour. It is a get out of jail free card. If Senna were step out of position, she would normally be punished but Tahm Kench can use Devour to get her out of an undesirable spot. Tahm Kench also brings poke and slows to his lane with his Q: Tongue Lash. Landing this hit slows the target allowing and applies one stack of An Acquired Taste. While they are slowed, Tahm Kench can to close gap between him and the target.

To aide in closing the gap, Senna can use her Piercing Darkness through Tahm Kench to hit the desired target to apply another slow. Once Tahm Kench reaches his target he can easily stack his An Acquired Taste another 2 times and Devour them to spit them backwards. This can result in a kill or a waste of an enemy summoner spell. Both are desirable. This combo makes Tahm Kench stick to you like glue and is all around annoying. If it does not go down like this, Tahm has his E: Thick Skin. This allows him to convert whatever damage he has taken into grey health and that grey health can be converted into a shield so that he may survive. Senna can then just heal him back up and it is rinse and repeat. During all this, Tahm is farming up the minions and getting all the gold so he can become tankier faster. Resulting in a more oppressive lane and Tahm and Senna being allowed to leave the lane to roam with his R: Abyssal Voyage.

Rumble, The Mechanized Menace

Rumble is a team fighting monster. Getting him his items will make him a force to be reckoned with. Fasting Senna allows Rumble to the gold he needs while being in a lane where he is safe to do so. Senna and Rumble's poke combined make this lane very oppressive for their opponents. Rumble can use his Q: Flamespitter to quickly clear the wave and burn his opponents to force them back. With Senna's Glacial Augent, it would not be hard for Rumble to get close enough to hit them with his Flamespitter. Rumble also has an ability to protect himself from poke and make trades go in his favor. His W: Scrap Shield gives him a shield and a burst of movement to close those gaps and ignore damage or he can run away if he needs to. With Rumble's E: Electro Harpoon, he can land even more poke on his enemies if they are too far away for the Flamespitter. Landing this harpoon does magic damage and applies a slow. This slow on top of Senna's slow makes Rumble just as sticky as Tahm Kench can be. After the laning phase, Rumble will have farmed lots of minions and have tons of gold. The items he would get would allow his ultimate R: The Equalizer to do so much damage in team fights. A perfect ult onto the back line or in the middle of a fight would either turn the fight in your favor or disengage from something unfavorable.

All in all, Senna's abilities make her laning phase so safe for her and her ally in the bottom lane. Senna is able to gather souls and her ally is able to farm up minions for gold. They both make it nearly impossible for their counterparts to lane. Senna and her ally get a lead in the bottom lane that they can then translate into helping others or carrying team fights later. During those team fights, Senna provides damage, healing, shields, and peel for her whole team that I think she is great in the ADC position.