Bells of Culling (Augmancy: Toll the Dead)

Augmancy. To cast this spell, you must know how to cast toll the dead. You do not need to learn or prepare this spells to cast it if you know toll the dead and have an appropriate spell slot available.

Until this spell ends, casting toll the dead can possibly conjure a one-way portal to the abyss. When you damage a creature with toll the dead and the creature's CR (or level if they have no CR) is less than the slot level used to cast this spell, there is a 15 percent chance that a portal will appear and pull the creature into the abyss.

At Higher Levels. When you cast this spell with a slot level of 7th level or higher, the duration of the spell becomes 1 minute with no concentration required, and the percentage chance for a portal to appear increases by 5 for every slot level above 4th level.