Thumper to summon Vulcanus Wurms

[DisRuptive1]

What if the Wurms on Vulcanus didn't come up to the surface unless they were attacking something? That something could be a deployable item that you stick in their territory that gives them cause to surface in order to attack it. Without this object, you'd have to build a sacrificial building in the worm's territory.

One of the ingredients could even be found on another planet so that Vulcanus isn't automatically the best first planet to go to.