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Whenever you cast a red spell, if this creature has fewer than three +1/+1 counters on it, put a +1/+1 counter on this creature.
Remove three +1/+1 counters from this creature: Add {R}{R}{R}.
If Runaway Steam-Kin has three or more +1/+1 counters on it after you’re done paying for a red spell, its ability doesn’t trigger at all. If it has three or more +1/+1 counters on it as its triggered ability resolves, it doesn’t get a +1/+1 counter.
Runaway Steam-Kin has to be on the battlefield for its ability to trigger. Casting it won’t trigger its own ability.
Runaway Steam-Kin’s triggered ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered.
