Zed becomes untargetable and dashes to an enemy champion, marking them. After 3 seconds, the mark triggers, dealing physical damage equal to 25/35/45% (+100% AD) of all damage dealt to the target by Zed while the mark was active.
The dash leaves a shadow behind for 6 seconds. Reactivating Death Mark causes Zed to switch positions with this shadow.
Reaper of Shadows: Zed reaps the shadow of the strongest foe slain under Death Mark, gaining (5 + 5% of the victim's attack damage) attack damage.
Reaper of Shadows is an important new mechanic, stealing the AD of the highest AD target killed. It basically snap shots their current AD on kill, so if they increase the amount they have you will have to kill them again to gain the increased amount. Killing a lower AD target will just keep you at whatever the highest value you have gotten is.