This card can't be played from the EX area.
At the start of your end phase, if this card is in your EX area, deal 1 damage to each enemy leader for every 5 Natura cards in your cemetery.
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Select an enemy follower on the field. Deal it 4 damage and, if there's a Valdain, Cursed Shadow on your field, put this card into its owner's EX area.
QIf I have two copies of this spell in my EX area and 5 Natura cards in my cemetery, do I deal 2 damage to each enemy leader at the start of my end phase?
AYes. Each copy's automatic ability will trigger.
QIf I have this spell in my EX area and 10 Natura cards in my cemetery, do I deal 2 damage to each enemy leader at the start of my end phase?
AYes. If you have at least 5 Natura cards in your cemetery, you will deal 1 damage. If you have at least 10 Natura cards, you will deal 2, and so on.
QIf I have this spell in my EX area and a Star Phoenix in my cemetery, and this spell's automatic ability triggers at the start of my end phase, can I pay 1 play point to summon the Star Phoenix with its activated ability?
ANo. Resolving an automatic ability is not the same as playing a spell.
QIf I have a Valdain, Cursed Shadow on my field, and I can't select an enemy follower on the field, can I still play this spell and put it into my EX area?
ANo. If you can't select an enemy follower on the field, you can't play this spell.