Question regarding a certain spell

[mcfly66]

Hi i would like to ask a question regarding a certain spell, I think the spell my be bugged, but before submitting a (possible) bogus bug report I would like to know what you guys think.

The spell is "44505" (drink fel infusion) the mobs which use it are "wretched bruiser" "wretched husk" and "wretched skulker" these mobs are contained in heroic and none heroic mode of magister's terrace.

The problem is when these mobs use the spell they hit for 20k+ on teir 6 equipped tanks (warrior/druid)

Is this a bug?, as i dont think this trash should hit for 20k on end game tanks especially in a 5 man instance.

Thanks for reading.