Moonlit Strider

Sacrificing this Spirit to protect another one is a cost, but it's also the loop. Activate the ability to give a chosen creature protection from the color of your choice, and the body that paid for the shield dies, which is exactly what fires Soulshift 3 to pull a small Spirit back from the graveyard. The two abilities feed each other by design. What sets this apart from most pump-and-protect effects is where the protection lives. Spend a card to deliver a one-shot instant elsewhere; here the ability sits on a 1/4 body and waits on the battlefield until a removal spell or a problematic blocker actually shows up. The four toughness is the patient half of the equation: it stonewalls early aggression and keeps the Spirit alive long enough to choose its moment, then turns its own death into a returned card instead of giving the opponent a free trade. The recursion clause sets the deckbuilding terms. A board of cheap Spirits worth fishing back makes each sacrifice nearly free in card terms, so the card wants a deep bench of low-cost fliers and utility bodies rather than one bomb to escort. The end result is a defensive engine hiding inside a wall: the toughness buys time, the ability rescues a key creature, and Soulshift means the rescue spends a body without spending a card.