To balance this system, the to-hit penalty for being surrounded could be forfeit.
In ADoM, when you are surrounded by monsters, your chance to hit decreases drastically. That's not entirely logical, since when there's plenty of targets around you then, statistically, your chance to score a hit grows
In Jade this system could be inverted. You don't get a penalty from being surrounded - the monsters get a to-hit bonus. This implies an evident tactic against surrounding - charge at one of the attackers at Berserk to bust out of the deathtrap!