Weve actually seen this happen a few times now, across a number of releases
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Unlike other Chocobo cards that get their stats boosted for just one turn, Sazh's Chocobo gets permanent stat boosts with +1/+1 counters instead
With that said, Kaien can be just as useful, or even more effective, than her Male, Effect-Monster counterpart
So its possible Norn could have invadedeventually, but certainly not in the span of the timeline of the set
Must first be Special Summoned (from your hand or GY) during a Duel in which your opponent has activated a monster effect in their hand or GY