Aethers dark twin is now accessible in minecraft! Once you make the portal (still work in progress), then you can travel in it, and go to the poisonous atmosphere. Little is known about this feature yet, as it is planned for later. In the latest stable version (Metroid Cubed 1.3.5), if you grab a portal using tmi, nei, or creative mode, then your game will crash entering the portal, for now. In the v2 alpha version 1.0.0 and later, the dimension is fully accessible (with a portal spawned in with creative mode) and generated properly. The environment is extremely hazardous, and you will die rapidly with anything less than the gravity suit. The dark and light suits are planned, which would reduce or nullify the damage taken, but the materials to craft them are not accessable as of v2 alpha 1.1.0