I would greatly appreciate feedback on a magic item I am homebrewing.
Constructious Heart
Wondrous Item, artifact (requires attunement). To attune to the Constructious Heart, you must repair the life of a construct. If the construct is grateful, it will heal the heart, and the heart will be in sync with your own. If the construct you repaired is ungrateful, it may crush the Constructious Heart.)
While attuned to the Constructious Heart, you may insert a key in the Constructious Heart. After inserting the key, you choose one construct creature (CR>9) within 120 ft vision, and that construct creature becomes your companion.
You may only have one construct creature companion using the Constructious Heart. If the construct creature companion dies, the Constructious Heart stops, and you must reattune to the Constructious Heart before using it again.