Esi has some experience being killed by Malar.
I think what you see from a secondary effect of their poison is a Constitution of 3 (but I may be confusing this with the dark spider poison), which makes your constitution modifier (-4). Given that a wizard has a d4 hit die, this tends to have unpleasant consequences.
Others may have better info on this, but it isn't exactly something anyone wants to experiment with in game.