How about a spell bomb and you can chose which spell is in, is 2x2 like giant bomb and only goes off in this radius, but has a max 3x3 once upgraded (Stays hidden like all other traps).
You can then choose from poison spell with same damage as current, freeze which deals no damage but freezes for an increasing amount of time as you level up and last option a lightning spell.
This can then be set for either ground or air defence only (not both) like a skeleton.
1 at th9 and last and final at th10
(I would only be in favour if SC tweeked current troop health)
Any feedback appreciated

