Gate Spell

[Halifex]

The Gate Spell would be a level 9 spell that is on the spell lists for clerics, favored souls, wizards and sorcerers, but not druids (because Druids don't get Gate in the Dungeons and Dragons books). The scrolls would be a rare drop just like other level 9 scrolls, but might be a special reward for high Purple Dragon Knight Favor, like Flawless Dragonshards are for high Gianthold Favor.

The spell would allow the caster and all nearby members of caster's party to move quickly from Eberron to Forgotten Realms or vice versa (like a Greater Teleport). It would only work from inside a danger zone. On rare occasions, a monster (marilith or jarilith, or orthon, etc) would come out of the gate and try to kill everyone, and the teleporting would not work that time.

[valarx]

Instead of operating only in danger zones, instead have it operate just like teleport/greater teleport.

However, there is a small chance that instead of being sent to the desired location, all accepting party members are instead sent to a mini-dungeon with a boss as you described. Recall/Release/Finished then works as expected, returning you to the last public location.