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Counter target spell that targets a creature.
If a spell is modal, use the target(s) of the current mode only for this check. Targets for the other modes are never selected.
If the spell’s target leaves the battlefield before this spell resolves, Intervene won’t resolve since it no longer targets a spell that targets a creature.
Intervene can only target a spell that is currently targeting a creature.
It means “targeting at least one creature” not “exactly one creature”.
