So in my last session as DM I had 2 Angry Mobs (from the monster builder) of sick villagers going insane. They were in quarantine, walled off (with bars like a giant jail cell) and banging at the door to get out. Not to go into details but a priest managed to get over the wall and was attacked by the mobs. The party wanted to help. So they formed a plan to open the door, slide the priest through and close the door immediately after. I was forced to tell them that a swarm is considered difficult terrain therefor they couldn't slide through the swarm that was blocking the door. Was that correct? Also was there any way for them to have saved him using controlling powers? They had no access to teleport.
In case you're wondering about the conclusion: The tank ended up entering the quarantine with the door shut behind him. Got knocked prone a couple of times by the mob but eventually picked up the priest and got out.
So after this session I realized that I don't quite understand swarm rules and have a couple of questions. I've copy pasted the compendium entry on swarms bellow:
A swarm is composed of multiple creatures but functions as a single creature. A swarm can occupy the same space as another creature, and an enemy can enter a swarm’s space, which is difficult terrain. A swarm cannot be pulled, pushed, or slid by melee or ranged attacks.
A swarm can squeeze through any opening large enough for even one of its constituent creatures. For example, a swarm of bats can squeeze through an opening large enough for one of the bats to squeeze through
Can a swarm occupy the same space as another swarm? Would their movement be subject to difficult terrain even if the swarm occupies only one square of the other swarm?
"A swarm cannot be pulled, pushed, or slid by melee or ranged attacks." Does this mean that they can be forced to move by area attacks?