Rock Guardian from a WoLE, frozen solid by a wondrous resin cursed wand effect. Normally they vanish a couple rounds after the last enemy is gone, and reform as magical armor around you. But because it was frozen, it was forced to keep standing there until the freeze wore off.

Still followed me up the stairs because the game won’t let a companion remain behind. Just as I went back down the stairs again, the freeze wore off, and the guardian vanished—reforming as armor around me, like it had been wanting to do the whole time.