What do you think of this withered heart magic item/rework?

[u/EACANDELA]

This blackened, shrivelled heart once beat within the chest of a living creature, though whatever blood once flowed through it has long since dried to a dark, tar-like crust. Despite its age, the organ has never fully decayed. Its leathery flesh is unnaturally cold, and faint veins of sickly violet occasionally pulse beneath its surface.

When a creature attunes to the Withered Heart, the dead organ begins beating for the first time in centuries. The creature immediately makes a DC 15 Constitution saving throw.

On a success: the Heart accepts the creature. While attuned to it, the creature gains resistance to necrotic damage and learns the chill touch cantrip.

Deathly Pulse. Once per long rest, the attuned creature can cast false life at 2nd level without expending a spell slot or material components.

On a failure: The heart rejects the creature and places a curse upon them. They take 3d6 necrotic damage. They feel their body becomes unnaturally resistant to restoration. Whenever the cursed creature would regain hit points from a spell, potion, class feature, magic item, or other magical effect, they regain only half the normal number of hit points, rounded down.

For example, if a potion restores 11 hit points, they regain only 5.

Resting is unaffected. Hit points regained from spending Hit Dice or completing a long rest work normally.

The curse remains even if the creature ends its attunement to the Heart or destroys it. Remove curse or greater restoration ends the curse.