Could Xuuvosic Teleport into the Enveloping Pit, drop a Fireball, and climb out? Is it apparent whether the floors inside are part of the magic item or added later? Also, I assume that the minions are happy to leave. But does that mean he can just tell them to get in, or would he need to take a standard action each to get them to enter?
Sorry to hold things up, but I'm hoping to avoid getting repeatedly zapped while we get all the pieces together to get up there, stay up there, see the enemy, and deliver enough damage. Although RJ having Dim Door, probably means that a tactical retreat isn't the only option.