Yes, good points. While it's probably not necessary to collect any ATK gems on this level since the hellhound is pretty easy to take down with the fire staff alone, I do think they will be valuable in the later levels, because eventually you will have to fight stuff. (If there should ever be any later levels, of course)
The last monster of the gauntlet used to be a spider, which made the fire staff a lot harder to obtain, but I felt like that might be too hard, so I changed it. Maybe that was wrong. Anyway, other possibilities would be to a) multiply all mana values by a certain factor to make the 20 % more accurate or b) move the fire staff to a later level, where Blaze is a lot weaker.
I must admit I never even thought about using _REP as mana
But yeah, since it works and people might find other uses for the _REP value, I'll probably leave it as it is.
Spells hurting that much in proximity to attacking enemies is indeed something that I couldn't find a workaround for. It seems like after asking a question, at least one turn has to pass before the script continues. By now I consider it a feature and not a bug
Still, if anyone has an idea how to avoid this, please tell me.
That being said, kieranmiller mentioned in chat that this level might be a bit overwhelming with choices, considering the player has to learn an entirely new mechanic, and also considering your comments so far this seems to be a valid point. So if I'm going to continue this hold, I'll probably completely rework this level anyway.
Anyway, Nuntar has expressed interest to make a hold of his own with this, which I'd very much look forward to. So for now, I think I'll leave the hold as it is and maybe try to further improve my own playing and architecting skills before I tackle this one again.