Unleash Hell

The caster chooses a 10x10x10ft cube and casts the spell. When the spell is cast, every creature inside the area must make a DEX saving throw against the caster´s DC. On a fail, they take 1d12 fire damage, as the cube becomes engulfed in flame. If a creature enters the area it must make the save again or take another 1d12 fire damage. When the spell is cast, 1d12 Imps appear, not hostile to you, but not under your control. If the creature failed its save, all Imps summoned get an opportunity attack against the nearest creature who failed its save.