Selfless Spirit gives a creature deck a sacrifice-based answer to destruction and lethal damage. Sacrificing it grants indestructible to creatures you control for the rest of the turn. Its flying body can contribute small attacks until you need the protection, and the ability does not require it to tap.
A token deck can preserve its army through Blasphemous Act, or sacrifice Spirit before resolving its own destruction-based sweeper. Recursion such as Sun Titan can restore the Spirit for another use when the deck supports that package. Indestructible does not stop exile, sacrifice, or toughness reduction, and creatures entering after the protective ability resolves do not automatically inherit the effect. Choose the timing around the board you actually need to preserve.
Choose interaction around the threat it actually addresses. Targeted removal, destruction, exile, and abilities on the stack require different answers, so no single protection slot covers every exchange. Leave the relevant mana available before committing to a threat, and identify whether the important resource is one creature, an entire board, or the spell that must resolve during the current turn.
Sacrificing the Spirit is the activation cost, so the creature is gone before the protection resolves. Opponents can still respond during that window. Reusing it through recursion can make destruction-based sweepers awkward for opponents, but an exile effect aimed at the graveyard can interrupt plans to bring the Spirit back.
