ThirdWizard said:
The best option at that point is to delegate to a player who does know the rules, which is a far better option than A or B. I'm not saying the player starts running the monster, but the player will say, "Okay, first you do a touch attack... Now an Attack of Opportunity... Now a Grapple check... " etc. Then, after the game, the DM can work on learning those rules for the next time the situation arises.
Given that it's "Attack of Opportunity then Touch Attack then Grapple check", and given that while I was reasonably sure of that I still had to look it up to be certain, it would appear that asking an experienced player isn't a workable option... and that's for Grapple, which is one of the least-obscure corner cases in the game.
Actually, what should have happened is that the player, in the whole round he had to plan his action, should have looked up Grapple in his PHB, and have it ready to hand to the DM to consult if needed. If the DM is using a creature known to grapple, then he should have reviewed the rules before play began.
If my DM doesn't know the grapple rules, then the game is mentally going to come to a screeching halt for me the second he starts making things up.
Ah, so we are talking about a slavish adherence to the RAW.
It throws everything out of whack with a big "Bwah?" as I try to understand just what's going on, and I'll stop the gameplay to try to figure out what is happening, because I'll have no idea what kind of strange thing is happening.
If you rules-lawyer an inexperienced DM, the most likely outcome is that he'll never DM a game again.
If you rules-lawyer an experienced DM in the manner you described, then you're proving a distraction for the whole group, and a disruption of the fun of the whole group. More than likely, after a few such instances, you would be politely asked not to return. The place for that sort of rules dispute is after the game session.
Either way, stopping gameplay as you describe is inappropriate.