View source for Ursine Domina

Applies a debuff (Plague) in an area around it which will cause damage done (to any target) by players with the debuff to heal it significantly.
Area purge skills are very useful here. Careful attacks are required.
It is possible to do this with single target purges but everyone needs to keep careful watch on their debuffs.
It's also possible for rdps to apply dps from outside the range of the debuff, if they can attack from far enough away.