Double Damage with Vampiric touch or gaze

Back when my character(N/E) was in Post-searing ascalon(he's now in kryta) i grouped only with henchmen. Randomly, against either devourers or grawl i would land double damage vampiric touches(and i think vampiric gazes). does anyone know why this was? it seemed to happen most often when i targeted a mob that went after my healer Alesia. Generally my group consisted of alesia, stephan, and orion(sometimes switched out for renya).

I could never determine if it had to do with a combo spell from one of my henchmen, or possibly an adverse effect on the mob(healing signet?), or even whether it was a bug. I didn't notice it happening in shiverpeaks or now in kryta, so could it possibly be a weakness of the mobs of ascalon?

If anyone could enlighten me as to how i landed double damage(and consequently double health gain) i'd be very grateful.

Thanks
-Bath

You probably hit a mob that had Frenzy on. (Warrior stance - Attack 33% faster, but take double damage.)

Khift, nice av. Yotian Soldier, correct? [sp?]

If you were previously unaware, Devourers are especially suspect to ice damage. If Death Swarm was one of these spells you cast, it was probably that.

Another instance would be Charr Blade Storms, who often cast Frenzy while attacking casters.

Or you could be getting critical hits maybe? Could be wrong, I don't know what % a crit hit increases damage by, or even if it applies to spells (or that type of spell specifically). Just a speculation.

No critical hits with spells, although, you will see discrepencies in damage if the target is wearing different armor on different parts. Headgear on elementalists while using elemental spells, for example.

Often, it's indeed frenzy.

Go play in the Ascalon Arena using defence ignoring spells: You'll see double damage a lot against warrior characters, because people use frenzy pretty frequently that early.