Call Dretch Horde

The caster summons 2d4 dretches and offers them a soul. In return, the dretches serve the caster unerringly for the duration, even performing suicidal actions. The dretches are, however, profoundly stupid and cannot understand orders more complex than 10 words. The caster cannot have more than 8 dretches in their service, no matter how many times this spell is cast. If the caster controls too many dretches, the remaining ones become uncontrolled.