[Magiclysm] Earthshapers cannot Stone Slumber unsafely

[Standing-Storm]

Summary

Bugfixes "[Magiclysm] Earthshapers cannot Stone Slumber unsafely"

Purpose of change

Report on the Discord of someone using Stone Slumber and then falling into lava because they were near a balrog mine. On the one hand, sinking into a balrog mine seems like a reasonable way to have real problems, but on the other hand, we're trying to avoid gotcha instadeaths.

Describe the solution

Check that the terrain you sink into is actually solid rock before moving you there.

Describe alternatives you've considered

Testing

Cast the spell above a balrog mine. It did not work and the mana was refunded. Cast it elsewhere, it worked normally.

Additional context