User blog comment:Niyanrudan/Arc, the Assassin of Time/@comment-77.58.207.79-20120519220456/@comment-5054161-20120520045334

the 180 bonus damage at level 18 is only applicable once, since any damage the marked target gets is increased by that amount, and the mark will be consumed, thus if there will be another damaging ability or attack, it's no longer amplified.

and he's a ranged champion. he throws his knives and daggers.