Avengers Assemble!
A tribal anthem that pays for itself, which is the design tension worth watching. Most static +2/+2 effects for a creature type land at one extreme or the other: cheap and inert (a lord you play and forget) or expensive and slow. This one bolts a card-draw engine onto the buff and gates it behind two conditions that a functioning board meets almost for free: attack with a Hero or land one this turn, and the end step refills your hand by one. Flash is what pulls it out of build-around territory and into the realm of a genuine tempo play. Because the anthem is live the instant it resolves, you can hold it up and drop it during combat to blow out a block, turning a Hero's attack into a bigger swing than the math your opponent counted on. And because the draw trigger fires at the beginning of each end step, casting it after you have already attacked with a Hero banks a card off that same turn. The restriction is the price: outside a deck packed with enough Heroes to make the anthem count and keep the condition live, it is a five-mana blank that stares at you. That is the honest cost of a payoff that generates recurring card advantage for as long as it stays online. Inside the right board it is an anthem, a per-turn cantrip, and a surprise combat swing folded into one flash enchantment.


