If you cant tell, my WHO knowledge is mostly from Tennant/Smith as a casual viewer
The effect is always active, even during opponents turns, so creatures equipped with flash can help buff your defense in the middle of combat
Under $10: Cryptbreaker, Zombie Master (if you're adding Urborg, Tomb of Yawgmoth), Balthor the Defiled, Crypt Ghast, Graveborn Muse, Grimgrin, Corpse-Born, Living Death, Dimir Signet, Beseech the Queen Pricey stuff: Sidisi, Undead Vizier, Relentless Dead, Lord of the Undead, The Scarab God, Mikaeus, the Unhallowed, Phyrexian Altar, Yawgmoth's Will, Vampiric Tutor, Demonic Tutor, Intuition, Cyclonic Rift, Tombstone Stairwell, dual lands, fetches, you know the stuff If you want to enhance your finisher potential even further, then adding Phyrexian Altar makes your Gravecrawler combos much more powerful, but that's a $70 investment
Heck, consider a heavy black control shell with Moment of Craving, Vraskas Contempt, and Gifted Aetherborneach of those cards turns Nightmares Thirst into an Ulcerate with upside, and an Aethersphere Harvester attack upgrades it into Grasp of Darkness
Amazon suggests the chance of finding the card in a collector booster pack is less than 0.00003%
