Let us Summon the Great Depths Worm (in addition to random wave chance)

[chaosmonkey]

I actually like the design that the Great Depths Worm is something you have to face at some point and can't simply ignore it like a lot of other bosses. This is not a request to remove its chance to spawn from the depths worms waves. Rather, this is a request to give us a way to proactively confront it to avoid it spawning when we are in the middle of a large caves build, similar to how we can summon deer clops on the surface at the start of winter. I'd argue that this is more necessary to the depths worms since it's almost entirely unpredictable as to when you'll have to confront it, unlike deerclops.