Iskall85, Cubfan135_ and Mumbo_ are all from the same world. the world is pretty much the exact same as Hermitcraft, except that Scar's crystals are actually magic. the crystals when dropped into a portal opened a path to Hermittpad.
This is also why Mumbo has no idea what a worm is, because worms are not in hermitcraft.

[will be updated over time]