I support this!
We need more PC.
EDIT: Thinking again... ok, if i have many pillars, say 6-7, it would takes 6-7 turns to destroy them. In this case i can even continue play pillars on that stack.
If i have a few pillars (2-3), i can let the stack dissolve and then start a new stack.
Yeah, i like it and i think it's balanced BUT multiple casts of this spell shouldn't stack or it would be OP.