Spell effect questions

[Trumanator]

I have a few questions about specific spells and their effects. I will probably add to this thread whenever I have a question, and others are free to do this as well.

1: The "Summon Behemoth" spell says that the caster cannot use magic while controlling the behemoth. However, I recently had three seperate Marshmasters all cast it, then I put the three behemoths under the command of one, and then sent them into battle against some indy barbarians set to skelly spam. All three cast spells during the battle. What exactly is the effect of summoning a behemoth?

2: When somone is poisoned, they take the rest of the poison damage at the end of the battle if they have any duration left. Does the spell Foul Vapors actually poison them, or does it simply deal poison damage? My reasoning is that it could be interesting to have a marshmaster cast it, then raise skellys a couple times, then retreat, and the enemy would take heavy damage with little losses to the C'tis player.