Sera, Breathkeeper Seraph

Flying, soulbond
As long as Sera, Breathkeeper Seraph is paired with another creature, each of those creatures has "When this creature dies, you may return it to the battlefield under its owner's control at the beginning of your next upkeep."

"Everyone looks to us and we can't doubt ourselves or worry about the fates of demons
when we have our own souls to protect." -Sera to Emily