It's hard to say how it would fare against four 20th level characters, but it does have some 1/month abilities that are pretty sick.
Its trick in the battle was to power word stun its opponent, then use the free rounds to gate in its buddies.
You might want to dig up the old thread started by Infiniti2000, who played the t'uen-rin. I think he had some suggestions on how to streamline it a bit. It is not a very efficient sorceror.
Overall, I would have almost as many reservations with introducing this monster in a campaign as I do with introducing the tarrasque while still calling it CR 20.
Its trick in the battle was to power word stun its opponent, then use the free rounds to gate in its buddies.
You might want to dig up the old thread started by Infiniti2000, who played the t'uen-rin. I think he had some suggestions on how to streamline it a bit. It is not a very efficient sorceror.
Overall, I would have almost as many reservations with introducing this monster in a campaign as I do with introducing the tarrasque while still calling it CR 20.