Soul Cage

6th-Level Necromancy
Casting Time: 1 reaction, which you take when a humanoid you can see within 60 feet of you dies
Range: 60 feet
Components: VSM($) (a tiny silver cage worth 100 gp)
Duration: 8 hours

As in Xanathar's Guide to Everything with the following added:
At Higher Levels. When you cast this spell using a spell slot of 7th level or higher, you can use a trapped soul an additional time before the soul is released and the spell ends for each slot level above 6th.

Source: XGE 161

Changelog