Chains of Divinity

This ritual combines the spells Summon Celestial, Magic Circle, and Planar Binding

The first 5 minutes of the ritual is spent creating an inverted Magic Circle and subsequently summoning a Celestial Avatar within the circle, where the Avatar is trapped for 8 hours. Once the Celestial Avatar of a specified god is summoned and trapped, the Chains of Divinity can begin.

After summoning and containing the Celestial Avatar, the caster begins to rip the very essence from the Celestial Avatar in order to release the God's true form within the Magic Circle. The Celestial Avatar must make a Constitution saving throw DC 35, or the Avatar will be destroyed, leaving behind the true form of the Avatar's God.

With this ritual, you attempt to bind a God to your service. The creature must be within range for the entire casting of the spell. At the completion of the casting, the God must make a Charisma saving throw with disadvantage, DC 35. On a failed save, it is bound to serve you Permanently. If the creature was summoned or created by another spell, that spell's duration is extended to match the duration of this spell.

A bound creature must follow your instructions to the best of its ability. You might command the creature to accompany you on an adventure, to guard a location, or to deliver a message. The creature obeys the letter of your instructions, but if the creature is hostile to you, it strives to twist your words to achieve its own objectives. If the creature carries out your instructions completely before the spell ends, it travels to you to report this fact if you are on the same plane of existence. If you are on a different plane of existence, it returns to the place where you bound it and remains there until the spell ends.