Any Damage you take for the next 6 seconds will be stored. When this ends, you will deal 100% of the damage taken back at your target up to 10000. In PvP there are diminishing returns on the damage stored as it increases.
When activated, it will store (count, not block) damage taken for 6 seconds. After the time, the user attacks the target for 100% of the damage stored, up to 10,000. This will have diminishing returns with stored damage during player killing.
Self-inflicted damage and typeless damage is also stored, meaning that Shadow Tendrils and Nex's ice prisons will be added to Reprisal's damage when possible.
Unlike Transfigure - which stores damage to later heal the user - the player is not bound or stunned in any way by using Reprisal.