This is a game where both you and enemies take turns spreading surfaces everywhere and where if you take a 1 damage hit, you create a 5 meter radius blood puddle containing more blood than exists in a human body.
Larian: "Hey, I have an idea, let's add in skills which turn all surfaces in the area into harmful ones!"
Larian 2: "Huh, you mean the player can target a certain area and turn it into harmful surface?"
Larian: "No, no no! I mean it turns ALL surfaces around harmful! What could go wrong?!"
These skills are awful because they affect all the surfaces, making it super-easy to spread fire or poison to your allies.
Meanwhile, the enemies with their much higher magical armor and much higher HP ignore and shrug off the scratch damage from the surfaces.
These skills suck. Ditch them.