Some great ideas for tactical combat so far.
I've seen a great example of even weak mobs getting out of the pits without climbing and even using their entrapment to their advantage.
A pair of kobold sorcerers and 2 warriors were injured and trapped in a 20ft pit as combat occurs above them.
Round 1: The Warriors swapping to their crossbows take ready actions to desperately pot shot at anyone they see at the top of the pit, while Sorcerer 1 casts Summon Monster 1 (Badger), Sorcerer 2 casts Grease on the rim of the pit.
Round 2: Warrior 1 accidentally shoots and kills another kobold that looks over the edge of the pit to throw a rope, body lands in pit.
Warrior 2 loots body and uses it as soft cover (+2 AC)
Badge appears Sorcerer 1 orders it to dig, Sorcerer 2 casts a second Grease on the rim of the pit.
Round 3: Badger burrows 20ft as a double move action, both Sorcerers assist with Profession(Miner)checks to make sure the tunnel doesn't collapse behind it. Warrior 1 moves back into tunnel using short spear as a support for the tunnel roof, Warrior 2 drags body to tunnel mouth as cover.
Round 4: Kobolds Diggy Diggy Hole. Party starts to investigate pit then the session ended.
Looking back a session later we realised this shouldn't of worked:
Rules state wrote:
Since it extends into another dimension, the pit has no weight and does not otherwise displace the original underlying material. You can create the pit in the deck of a ship as easily as in a dungeon floor or the ground of a forest.
Also there is no rules regarding what happens to creatures still in the pit when the spell expires. We ended up ruling that the kobolds had escaped into the other dimension and ended up with quite a surprise 5 levels later when we heard of a kobold adventuring party doing quite well for themselves from a planar traveller. XD