Dealing with Regeneration in Combat?

Currently there is no way to do that. I find it rarely matters and most combat ends after 2 to 4 rounds. The regen creatures get to negatives so low that. you just kill them off if the pcs have a way to stop it the regen. Easiest way if it really is important is to just edit by pressing e on keyboard and unchecked the box. the creature that lose the Regen for 1 round edit the creature and turn off fast healing the moment it hit with the thing that suppresses it. at the end of that creatures struck turn. check it back on. It less clunk then hitting d then having to input damage = the heal amount press ok. I would not worry about pc figuring out about the Regen and make the knowledge or heal check, as it going to be pretty obvious that it is healing or has dr with the wounds start to close. Use the knowledge check to see if the pc know what stops the healing. dc 15 checks are easy for the wizard or cleric to do so, most of the time they don't even have to roll to make the check. take 10, 1rank+3 class skill+ability score mod. most of the time = more then 15. Melee characters are not going to care as they are just going to keep pounding on it, until the one with the knowledge check does what is need to stop the healing process.