The Soul stone

Shroud
{4}: You gain control of this artifact. Any player
may activate this ability.
{x}, {t}: You gain X life. Repeat this process once.
{x}, {t}: Create up to X 1/1 white spirit creature
tokens with flying and lifelink. Only activate if
you control 3 or more Infinity Stones.
{x}, {t}: Return all creatures with converted mana
costs X or less to the battlefield under your
control. Only activate if you control 5 or more
Infinity Stones.