This mod is basically just one dimension and almost everything what you do is poisonous, so if you just search for a mod that hurts, this is it
I recommend you to download JEI mod, because that crafting recipes are incredible
And when you want to enter the toxic dimension you just must make nether portal but with crying obsidian and ignite that with Toxic Igniter (You can see how to craft it in JEI)
(If you see some mistake in this text write it in the comments please I’m from Czech Republic)