Thinking about it afterwards, it seems that the nature of the bug is that the spell keeps being recast on "full auto" with no cooldown until the caster's mana pool is empty. Conjecture, but it seems to describe what's happening. One blast is kinda serious but in line with combat; many blasts are really OP and few players are going to survive it. Hard to say if it's an actual bug (I'm guessing it is if reports are inconsistent, though that "until the mana pool is drained" could also explain that) or if someone had a "maybe this would be cool" idea and "actually, no it wouldn't" was lost in the post.
