The Spectre key will transport you to hell the drop you out of the world as no loading any floor http://imgur.com/6nYoImb

The issue persists in 1.10.2, but not when RT is the only thing installed.
I'm currently running through my modpack one at a time to find the conflicting mod.

@NezcalSpindrake You can also run through it half at a time, that's faster.

So... None of the mods cause a conflict in new worlds. The issue only exists on the server where the mod was added after a while of playing.

So I tried to record what was happening, and it freakin worked. It took a very long time to do so however.
On another note, a Slime Island spawned inside the spectre dimension, should I report that to TiCon or should I make a new bug report here?

Can you reproduce this with only Random Things installed?