Todash is a place of being that allows someone to travel between universes. It is not a "normal place" and is usually triggered by a powerful event or object. The todash state is usually accompanied by the "kammen" or chimes, which produce an unpleasant or pleasant sound similar in effect to a thinny.
Alain Johns goes todash twice when he enters Maerlyn's Grapefruit to try and save Roland's soul which is trapped inside. Once though and once to get back. The layers of darkness go deep.!
There are several ways that a person can "go todash". Todash occurs in certain circumstances when someone dies,awareness while "Stuck".
Going todash is very dangerous.The point is - it is possible to get stuck between worlds in the "todash darkness", where you can't get back from.