Banish this card from your cemetery: Select a Mystic King on your field and give it Storm.
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Deal each enemy follower on the field damage equal to the number of Chess cards in your cemetery.
QWhen I play this spell, does it count itself among "the number of Chess cards in your cemetery"?
ANo, it doesn't.
QCan I only play this spell's activated ability when it's in my cemetery?
AYes, that's correct.