What is 5e summon greater demon?

Summon Greater Demon is a 4th-level conjuration spell in the 5th edition of Dungeons and Dragons. It allows the caster to summon a powerful demon from the Abyss to serve them temporarily as their ally. Here are some key features of the spell:

1. The spell has a casting time of 1 hour and requires the caster to perform a ritual that involves drawing a circle and invoking the demon's name. The spell also requires a vial of blood from a humanoid sacrifice.

2. When the spell is completed, a demon of CR 5 or lower is summoned. The demon is hostile to all creatures except the caster and will follow their commands for the duration of the spell (1 hour or until the demon is killed).

3. The caster can attempt to control the demon by making a Charisma check against the demon's Charisma score. If the check succeeds, the caster can issue commands to the demon on their turn as a bonus action.

4. If the caster loses concentration on the spell or the spell's duration expires, the demon will become free-willed and can act as it wishes.

5. The spell can be cast at higher levels to summon a demon of a higher CR, with a maximum of CR 8 at 9th level.

Overall, summoning a greater demon can be a risky proposition, as the demon may turn on the caster or cause chaos and destruction if not controlled properly. However, with the right planning and tactics, a summoned demon can be a powerful asset in battle.