Dark Endurance is a common Instant card from Edge of Eternities (EOE), collector number 93. Current market price: $0.14 (foil $0.20), TCGplayer market prices via Scryfall.
This spell costs {1} less to cast if it targets a blocking creature. Target creature gets +2/+0 and gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)