Source: Unearthed Arcana 11 - That Old Black Magic
7th-level conjuration
Casting Time: 1 action
Range: 60 feet
Components: V, S, M (food worth at least 100 gp, which the spell consumes)
Duration: Concentration, up to 1 hour
You summon a hezrou that appears in an unoccupied space you can see within range. The hezrou disappears when it drops to 0 hit points or when the spell ends.
The hezrou’s attitude depends on the value of the food used as a material component for this spell. Roll initiative for the hezrou, which has its own turns. At the start of the hezrou’s turn, the DM makes a secret Charisma check on your behalf, with a bonus equal to the food’s value divided by 20. The check DC starts at 10 and increases by 2 each round. You can issue orders to the hezrou and have it obey you as long as you succeed on the Charisma check.
If the check fails, the spell no longer requires concentration and the demon is no longer under your control. The hezrou then focuses on devouring any corpses it can see. If there are no such meals at hand, it attacks the nearest creatures and eats anything it kills. If its hit points are reduced to below half its hit point maximum, it returns to the Abyss.
As part of casting the spell, you can scribe a circle on the ground using the blood of an intelligent humanoid slain within the past 24 hours. The circle is large enough to encompass your space. The summoned hezrou cannot cross the circle or target anyone in it while the spell lasts.