Thanks everyone for the responses.
So it sounds like its gas traps... and the problem is that fireball or maelstrom click the trap and then set off the gas explosion almost instantaneously, before you can do anything to get away. So it's often insta-death for a fragile mage.
Switching the resistance to these from magic to fire would help; most fire mages have decent fire resist. And it makes sense that fire resist is something a fire mage must cultivate to stay safe.
Ideally, you'd be able to mostly avoid fiery deaths by playing smart - staying away from barrels, support beams, etc while you blow things up. But right now the gas traps defy all that since you usually cant even see them. Nerfing or negating that damage would help.
Despite this one complaint it's a great game, keep up the good work!