You have mastered the ability to bind souls into constructs. You gain the following abilities:

• You learn the Soul Cage spell if you did not know it already. This does not count against the number of spells you have known.
• You can expend a spell slot of fifth level or lower to permanently trap a soul you have obtained with Soul Cage in a diamond worth 500 GP or more.  Trapping the soul requires one hour. While the soul is trapped within the diamond, you cannot use the features as described in the base Soul Cage spell with this particular soul. You can only store one soul in a diamond at one time.
• Using the diamond, you can construct a golem. The time and material cost is as described by the Manual of Golems in the Dungeon Master's Guide. This golem consumes the soul diamond that you created.
• In order to control the golem, you must attune to it, as if it were a magic item. It obeys your verbal commands. If you lose attunement to the golem, it goes berserk, and acts according to how it was treated.