Bendris Noulg said:Beats me... I've been using opposed rolls over static 10+ for nearly 3 years now (Defense, Spell DCs, and most anything with a value 10 or higher).
But that's not quite what this is.
"Players Roll All the Dice". The DM does not make an attack roll. Instead of the monster rolling 1d20+bonus+adjustments and checking against the character's AC (10+bonses+adjustments)... instead the monster is assumed to roll 12+bonuses+adjustments and the PLAYER rolls "AC": 1d20+AC Bonuses+Adjustments.