Maximum lane sustain and utility.
Improved attacks and sustained damage
Attacking and moving builds energy stacks. At 100 stacks, your next attack heals you and grants increased MS.
Excess healing on you becomes a shield.
Takedowns on enemies grant permanent Lifesteal.
Deal 7% more damage to low health champions. Gain AD/AP after kills or assists.
9% attack speed, 10 ability power or 6 attack damage
Gain increasing amounts of AD or AP, Adaptive over the course of the game.
Gain 10% CDR when you reach level 10. Excess CDR becomes AP or AD, Adaptive.
Fleet Footwork is a fantastic rune choice for lane sustain and the movement speed needed to get into position for fights.
Overheal pairs very nicely with Fleet Footwork for a reliable shield to keep you healthy going into trades/fights.
Legend: Bloodline allows you to further sustain and build your Overheal shield in lane to mitigate poke damage and out-trade your enemy lane opponent.
Coup De Grace is the go-to rune for reliable squishy target damage when paired with your passive and massive amounts of crit.
Gathering Storm is your late game insurance policy. With a game that goes to 30 mins+ you'll be dealing massive amounts of damage.
Ashe is one of the few ADCs who prioritize CDR, largely because her abilities provide so much utility. Transcendence let's us hit cap ASAP without worrying about going over.