Fane was super sick with fire/poison
Until you hit about level 13ish (or so) every fight will feel that way. My recommendation is to stay in Act II for as long as possible (until you're at about level 16 or so) and then just play the rest of the game. It will seem easy, but after a long draft of beating your head against the wall, it'll be a breath of fresh air.
You can make poison potions heal as much for fane as regular potions do with normal heroes (at least to a fairly large, 4 digit number?). If geomancy skills aren't covering it, I would hazard a guess that either you are fighting things in a way that you are under-leveled or out numbered.
What do you have him specced to do?
No, even with the mask effect on Fane he is still treated as undead for healing/poison spells.I assume turning him into any non-undead race also removes the downsides of being undead, since it gives you other racial benefits (lizard speak, cannibalism for elves etc).
There are debuffs that reduce healing, some that block it outright too. Never had issues with Fane either as melee or ranged on honor mode, but depending on how far you are be careful of splitting too far in multiple paths, and whether you are rolling lone wolf or not. Whenever I make a warfare character it's either full war+ranger, war+scoundrel, or war+constitution and maxed out str/cha, or dex/cha. Leave gear bonuses to build magic so you don't gimp yourself. If it's not a melee tank/2h faceraper, get stench/smelly (whatever makes you less likely to be targeted) and pickup a skill that summons a pet + have it out before you engage.
Also: Can I play the same game saves on Desktop and Laptop if it's on Steam? It's got the little cloud icon next to it on my Library. So is that a yes?
We’re in Act II at level 11 right now so hopefully not too much longer for it to smooth out. It definitely feels like the game is intentionally trolling us sometimes (that fuckin’ scarecrow chilling just outside of town when you first land in A2, the fuck). I guess we’re slowly learning lessons though, stuff like “just don’t talk to it” and “never stand next to one another before combat” seem like good guidelines so far.
That pet pal talent is also the best damn thing in the game, IMO.