I was playing ADOM, basically on Easy (Corruption/hunger on, easy monster high loot drops), with a N+ dark elven necromancer (Amulet of order and necromancy helps keep me in neutral alignment, I find. I was trying to stay neutral, so that's not a bug) when I come across the shambling mound. By the description in the monster memory, this is basically a walking shrubbery pile of plant matter. I think it should suffer extra damage from being a plant (admittedly, a living one) that has been set on fire.

Also, Lizard men take extra damage from fire. But I was wondering, could they get boosts to their speed for getting "Heated up" like drakelings do? It's merely opinion, but I believe that would balance their (fairly easily, with the right spell/class) exploitable weakness for fire. Heck, even as a level 1 elementalist, I have no fear of these guys. I think this would balance them out. They get burned and, assuming they survive the extra damage, they get heated by the fire and can move faster.