Without some visible indication that an attack is being charged, combined with the attack being an insta-hit, I don't see it being an ability conducive to fair play. The same goes for the Gamo Tan ability, which it seems can reach temperatures comparable to napalm in the space of a single second, and requires no forewarning or travel time between caster and target. That's an instant kill against any character without a resistance to heat, since they would have no way to see it coming or counter it once activated.