DonTadow said:Would it just be a natural d20 roll or adding something like wisdom or (perception?) to it.
Assuming it works as it did in the previous DDM version, it's a straight die roll. It's to simulate 20% and 50% miss chances without using any die other than a d20.
Remember, this is a DDM only thing, mind. I suspect the mechanic will be utterly different in the RPG rules for 4e.