Selfless Sacrifice

Sacrifice target creature you own then return a different creature with a mana value less than or
equal to the target creature's from your graveyard
to the battlefield with haste.
Chronicle {3}{w}{w} (You may cast this card for its chronicle cost instead to play it as a legendary enchantment that triggers as it enters the battlefield and on your upkeep)
The brief moment they share together as they pass is
enough to make them continue for eternity.