green hydra cards mtg Theros Beyond Death Rare Ironscale #296 double the number of +1/+1 counters on this creature. Zaxara, the Exemplary Hydra Tribal

Even something as simple as Syphon Soul would let a 6-mana spell cascade in a 4-player game

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They also need some method to finish you off, which is often a card which doesn't do much for the deck otherwise

Yes, they are

The format's only remaining OG mana-cheat deck is Affinity, named for a mechanic that reduces the cost of spells with affinity by one generic mana for each artifact the card's caster controls