Blood Bind

You attempt to bind one fiend or un-dead creature of your choice that can see or hear you. The creature must be of a CR equal to your player lvl or lower. That creature must then make a wisdom saving throw against your spell save DC. If it succeeds the creature is immune to being bound this way for the next 24 hours and the caster takes 3D12 necrotic damage. If it fails that creature is now bound to your servitude for the next 24 hrs. Upon completion of this time the creature may choose to sever the bind or keep it intact. If severed the creature is returned to its original plane of existence and cannot be bound by this caster again. If the creature remains under the bind it is friendly towards you and your allies. You may summon a bound creature by casting this spell again and saying its name. Only the parchment component is required to cast the spell in this way. 

Casting this spell drains the user physically and spiritually. Upon completion of this spell the caster's temporary HP are reduced by half. A long rest or a Greater Restoration spell can be used to recover their HP. Binding a fiend or undead does not come without consequences. For the next 1d4 + 2 days the caster is haunted by vivid nightmares. 

A bound creature may communicate, if able, with the caster via telepathy. whether or not the creature decides to remain under your servitude is biased on your relationship and how you treat it. If treated poorly the creature may undo its bind to you at any time after the 24 hour period of the initial cast. 

It is an action to summon a bound creature and an additional action to send it back.