Rule 702.112a

Awaken appears on some instants and sorceries. It represents two abilities: a static ability that functions while the spell with awaken is on the stack and a spell ability. “Awaken N—[cost]” means “You may pay [cost] rather than pay this spell’s mana cost as you cast this spell” and “If this spell’s awaken cost was paid, put N +1/+1 counters on target land you control. That land becomes a 0/0 Elemental creature with haste. It’s still a land.” Paying a spell’s awaken cost follows the rules for paying alternative costs in rules 601.2b and 601.2f–h.

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