I was just about to edit to add one more thing… I have faith in Daishain's ability to offer us a solid challenge, but one within our reach. We might not all survive, heck, we might lose. But I don't think he's the kind of Dungeon Master to decide he's going to hammer us. He is taking our condition into account, and crafting something that will be… interesting to say the least.
Perhaps if it looks bad, such as a vampire and 15+ guards (Maybe less, even) Velon will immediately sound the retreat. He could wish the invisible ones with fly good luck, and everyone else goes back into the control room and teleports as fast as possible.
Daishain, could you let us know if a) teleporting or b) breaking the Queen free will take more than 1 round of action?
Using the teleport scroll will just take an action, but everyone going must have physical contact with each other, which may add to prep time if scattered.
The fast way of freeing the queen just involves brute force damage to the thing she's in. A big hammer or axe would be ideal, elemental spells wouldn't help much, but thunderous or force based ones would work fine. How long it will take depends on how much hurt you can pile on it at once.