Karplusan Yeti

{T}: This creature deals damage equal to its power to target creature. That creature deals damage equal to its power to this creature.

Ninth Edition

{T}: Karplusan Yeti deals damage equal to its power to target creature. That creature deals damage equal to its power to Karplusan Yeti.

"What's that smell?"
—Perena Deepcutter, Dwarven Armorer

Ice Age

oc
T: Karplusan Yeti deals an amount of damage equal to its power to target creature. That creature deals an amount of damage equal to its power to Karplusan Yeti.

Giving either creature first strike does not affect the ability.

If this leaves the battlefield before its activated ability resolves, it will still deal damage to the targeted creature. On the other hand, if the targeted creature leaves the battlefield before the ability resolves, the ability won't resolve and no damage will be dealt.