Caitlyn's basic attacks generate 1 stack of Headshot (doubled when attacking from brush). Attacks against towers will not grant any stacks.
At 7 / 6 / 5 stacks, her next basic attack will deal 50% AD bonus physical damage. The bonus damage is tripled against minions and monsters, and against champions the enhanced attack ignores 50% of the target's bonus armor.
Runaan's Hurricane will generate stacks for every enemy hit. However, as with all one-use on-hit effects, the bonus damage will only apply to the primary target.
COST: 50 / 60 / 70 / 80 / 90 mana
COOLDOWN: 10 / 9 / 8 / 7 / 6
Active: After a 1 second casting time, Caitlyn fires a projectile that deals physical damage to all targets it passes through. Each target hit after the first takes 10% less damage, down to a minimum of 50% of the original damage.
Enemies hit while protected by a spell shield will still be considered when calculating damage for subsequent hits.
Yordle Snap Trap
COST: 50 mana
COOLDOWN: 20 / 17 / 14 / 11 / 8
Active: Caitlyn sets a trap at target location that arms after 1.1 seconds. Enemy champions who come within 67.5 range of the trap will detonate it, becoming rooted and taking magic damage over 1.5 seconds. The trap also grants true sight of the target for 9 seconds.
If Caitlyn loses sight of her target before she locks on, the skill cancels. It is not put on cooldown nor will it consume any mana.
Ace in the Hole grants true sight of the target while locked on, and becoming stealthed during the channel will have no effect. The missile will follow and can still hit stealthed champions, effectively revealing their position.
Clones will intercept the missile, as they are classified as champions for targeting purposes.
Once Caitlyn has started channeling, she is unable to cancel the ability herself. This is unlike many other channeled abilities, such as Nether Grasp, which can be canceled by commanding Malzahar to move.
If the target dies or becomes untargetable during the channel, Ace in the Hole will be canceled and put on a 5 second cooldown. This will not refund the mana cost.
If the target dies after the bullet has been fired, it will continue toward their corpse and can still be intercepted. The ability will go on full cooldown.
The missile will continue to follow untargetable champions, but will fizzle upon reaching them unless they become targetable before it would hit.