Rzach said:Jail cells can hold Eladrins if the doors are solid and there is no way an Eladrin can see outside the cell. Teleport requires line of sight.
What about underground cells? Doesn't there have to be free space to walk through in the Feywild for the teleport to work, so Eladrin will not be able to teleport out of a traditional excavated sub-basement dungeon cell?