I don't think it should be castable in combat. The spell just requires a bit of set-up, I think it will be fun to play around with, the control effects and damage are good, especially for a Cleric or Bard. The glyph should be invisible, though the spell description allows an Int (Investigation) check to spot. But I say just make it invisible. You'd just put it in path the enemy would take to reach you after you start the battle with a ranged attack. This AI will barrel right through it, I imagine. The spell's range would probably need to be extended for this to be useful though, otherwise one would probably trigger combat while trying to place the glyph.
Not good against flying enemies though, given all Larian's blast radii are flat.
