This spell functions like soul cage, but modified for thrall-making.

When the humanoid dies, you trap a fragment of its soul and reshape it. For the duration, you gain the following abilities, each usable once unless otherwise noted:

• Blood Echo (no action): Gain advantage on one attack roll, ability check, or saving throw.

• Thrall Eyes (action): See through the soul’s eyes as it lingers near its body, gaining darkvision 120 ft and advantage on Perception checks.

• Crimson Sentinel (action): Summon a spectral thrall that takes the Help action for you.

• Siphon Vitality (bonus action): Regain [roll]3d6[/roll] hit points.

• Command Shade (bonus action): Force one creature within 30 feet to make a Wisdom save or be frightened of you until the end of your next turn.

If the original creature was willing at death, you may instead bind the soul into a temporary thrall for 1 hour (DM determines stats: typically a CR 1/2 humanoid spirit).