How does power guard work exactly?

I know the wing gives attack buffs, but our dks always live passing the tail, I usually see them taking 32,500 damage or so on my screen. Maybe I need more str or something, oh well. Oh yeah, if your level is below the monster's, you take more damage too don't you? Was 157 when it happened.

Those are factors that does not really change a lot. At most, like 1k hp.

Weird though. Unbuffed, HT-tail should at most deal 23k damage to you without any PG or Achilles.