Utilize souls v.2.5

When a creature dies, you can capture its soul in the container. If the creature has an Intelligence score of 5 or higher, it can make a Wisdom saving throw against your spell save DC to resist this spell. If the creature's saving throw fails, its soul is transferred to the container, which you can then use to do various things. The uses of souls are detailed below. The container can hold 1d6 souls (this number is determined when you first attempt to cast the spell with a container. This number cannot be changed after that. Each container gets its own roll).  If the creature's soul is unavailable (e.g. captured by the Magic Jar spell) or the creature doesn't have a soul, this spell fails. 

1) Consume:   You use your action to consume some of the souls in the container. You regain 1d10 hp per soul you consumed.  You can consume multiple souls in one action. 

2) Summon:    You summon the creature whose soul you have trapped. Its stats are the same as when it was alive, but they are now considered undead, and they must follow your verbal commands to the best of their ability. It understands all languages you know, but cannot speak. It takes 1 minute to summon a creature, and it returns to the container after it has been out of it for 1 hour. If its hp reaches 0, its body turns into dust and the soul is lost. 

3) Spells:   As an action, you can expend a soul to cast a lvl 4 or lower spell that you know without expending a spell slot.