Clemency: change to HoT, make instant and off GCD, possibly lower MP cost slightly.

This skill is weird.
Practically useless in a skilled group.
Practically OP (for a tank) in an unskilled group.

Moving it off GCD makes it more useful in a skilled group since it won't necessarily drop DPS.

Making it a HoT will remove it's burst, making it less powerful in a unskilled group.