Execration

You attempt to annihilate a creature or entity you can see within range by banishing its essence to the void in the Far Realms. You must be able to see the target, and the target must remain within range for the entirety of the minute-long casting time, and you cannot take any other bonus actions or reactions that might inhibit the verbal or somatic components of the casting, for the spell to take hold. 

At the end of the casting, the statuette of the target disintegrates, and the target must make a DC 30 Charisma saving throw with disadvantage. No luck points, legendary resistances, or similar abilities can be used to influence the outcome of the saving throw. If the target succeeds the saving throw, the target's essence is banished to a harmless demiplane, where it remains in stasis for 1d100 x 10 years. While in stasis, the target is incapacitated and paralyzed, doesn't age, doesn't require food, drink, air, or sleep, and cannot leave, send, or receive anything outside the plane. After the determined amount of time passes, the target reappears in a safe place on it's plane of origin. If the target fails the saving throw, it's essence is banished and destroyed permanently, with only an entity of the Far Realms being capable of resurrecting the target. Anything short of this fails, including divine intervention, wish spells, and even time travel. 

A viable target for this spell also qualifies as anything having a fair amount of its essence within range that is a direct extension of the target's personal will and being. A servant or creature created by an evil god is not enough of a connection to the god to execrate it, but if a part of the god's spirit were to possess said servant, it would be a sufficient target. 

The likeness of the statuette must be made to the specific target. A single statuette can be made in the likeness of multiple creatures that have identical bodies, like a balor, but it must be adequately made to tailor the target. As such, a statuette of a simple skeleton, or even one with robes and holding a staff, is probably not sufficient to execrate a lich.