It bears the Crew ability word - specifically Crew 3, requiring you to tap any number of creatures you control with total power of three or more in order for Cultivator's Caravan to become an Artifact Creature
Its often just turning a mana dork (think Dyad Arbor ) into something that ends the game
Then add these aura/enchantress payoffs: Ghostly Dancers, Hallowed Haunting, Sigil of the Empty Throne are the best token generators for Enchantress imo, don't need Ghostly Prisons when you have an army of 4/4 flyers that can also swing and win
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Giving creatures the ability to attack or tap on the same turn they enter the battlefield under your control lets you quickly apply pressure to opponents through big stats, attack triggers, and powerful abilities the table would otherwise have a turn to respond to
Despite it being an uncounterable creature that you can cast at flash speed, one of the most common things to do with Hullbreaker Horror is cheating it into play with a card like Polymorph