Game Mechanics: Necro heal recourse incorrectly dispellable

[Potus]

Game breaking bug? This is necro heals we're talking about. LOL. What encounter is being exploited by this?

It's classic. Sorry. Necros commonly used it on raids to sometimes spot heal. That's why Stalking Probes/Holgresh Elder Beads were sought after. You'd lich, give people heals, then dispel it.

Look, strategy guide, right here

7) You are a patch-healer. Use spells like Shadowbond and Shadow Compact to deliver a smooth flow of heals onto the target. This spell line costs very little mana, and can help alleviate the amount of healing the Healer must do. If you keep your first Buff Slot open, you can even Cancel Magic the negative recourse of the spell, creating some very mana efficient patch healing.