AoE? Parasite Egg? do it yourself?
its kinda rough in the situation you describe though. Crucible, uniquely it seems, has 2 very important flags that are really far away from any towers so its possible to just dominate that whole area with minions.
yet more evidence that Crucible is a horribly bad map.
the idol selling thing will probably be patched out eventually if what i've heard is correct though, so..uh...just wait?