[Psitticine]

If I remember correctly, the priest Starspawn have a 5% chance of coming back non-feebleminded. The hero Cthul . . . err, the guy with a name something like Cthulu the Stargazer has only a 2% chance of getting mind-fried.

On a side note, if you send anybody into the gate, send Illithids along with them with the Guard Commander order. Only Illithids will appear on the battlefield if the summoner gets attacked by what he contacts, and this is a great use for the artifact that allows your 10 guards instead of the normal 5.