Forum:Evilswarm Nightmare

If my opponent activate "Advanced Heraldry Art" to summon 2 "Heraldic Beast" monster, can i activate "Evilswarm Nightmare" effect to change that monsters to face-down defense position, or it miss timing and i can it after "Xyz summoned? Elvin Kara (talk • contribs) 19:31, December 14, 2013 (UTC)