ToME: the Tales of Maj'Eyal

I'm playing around with a skeleton poisoner rogue, currently at 3,4,4,0 poisons, and I saw them healing from the Leeching Poisons. I was recently doing an Arch mage and when I got the (forgot name of the skill, but it gives 20% immunity to my own spells per level) hole in the middle skill to level 5, my cleansing flames stopped working (I was immune to it, so got no benefit). Skeletons are immune to poisons...

Yes these are both intended. The skeleton isn't the one having the poison applied to them, so it works just fine. And wildfire archmages specifically have negative synergy with Spellcraft.