Adanto Vanguard is a uncommon Creature — Vampire Soldier card from Ixalan (XLN), collector number 1. Current market price: $0.16 (foil $0.73), TCGplayer market prices via Scryfall.
As long as this creature is attacking, it gets +2/+0. Pay 4 life: This creature gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)