Quite a bit of spell effects state that they work once in a round.
For example, Balor Nimbus (Spell Compendium p24):
each round, the flames deal 6d6 points of fire damage to any creature grappling you (or any creature you grapple) on your turn.
When exactly on my turn does the effect happen? Am I right assuming that the effect happens once on my turn at the earliest possible moment? There ought to be a clear ruling somewhere, I just can't find it.
To clarify a bit, consider this situation (Initiative order is X then Y then Z):
- On round 1, X casts Balor nimbus (standard action), then Celerity (swift action), then starts a grapple agains Y (standard action from Celerity) and gets a hold. Does his opponent get burned right away? Or does the damage occur at the beginning of the round?
- On Y's turn he breaks free.
- On Z's turn Z starts grapple with X and gets a hold.
- Next round, X breaks free from grapple (standard action). Does Z take damage from Balor Nimbus?
Bonus question, to complicate things more:
- X has Improved Grab ability and Balor Nimbus on. X grapples Y with one hand.
- It is start of X's turn. Does Y take damage from Balor Nimbus? If yes, when X grapples Z with his other hand, does Z take damage from Balor Nimbus?
If Balor Nimbus is too hard, let's try Wall of Fire.
"Once each round" effect: happens at the beginning of the round or at the earliest possible moment at the round? Goes off once at some moment in time or once for each creature affected, possibly at different moments?
I'm interested in an answer supported by the rules.