In Bard's Tale III the C64 version you could summon a strong monster / demon and you had to continuously exert your mind to control the thing.
In every turn it had the chance to break free, attack you, go berserk. Then you had the possibility to cast a CALM spell, so the monster was yours again.
Mind controlled Alien should have a chance to break free every turn and an equal chance to go berserk every turn if broken free.