So if two people are caught in a blizzard sphere, and one had already acted, and the other had not, they would both take damage when the spell was first cast.
The guy who had not had his action yet, would not take damage before or after his trun, since he had already taken damage that round. If he simply walks out of the AoE, he does not take damage again.
The next round there is one guy in the AoE, and he has not yet had any opportunity to react.
So when does he take damage?
- At the beginning of the round. Because he had a higher initiative than the caster last round, He has not acted since the spell began. It seems unjust that he gets effected twice just because he had high initiative last round.
- Before the targets action. Same as above.
- After the targets action. If he is still in the sphere after he acts, he takes damage. This seems fair and workable.
- Upon the casters / poisoners action. It might be before or after the target acts, so he might still be effected twice before a single chance to react. Also, if the caster is dead or otherwise out of combat, that could be a problem. I would probably just substitute end of round in that case, in which case why not just start with that condition.
- End of Round. Assuming the target is still in the AoE at the end of the 2nd or subsequent rounds. Also seems fair and workable.