Fenrir the Nordic Wolf

Cannot be Normal Summoned/Set. During your Main Phase 2, if an "Aesir" monster is on the field, you can Special Summon this card (from your hand) to your opponent's side of the field in Defense Position. If an "Aesir" monster is not on the field, destroy this card. At the start of your Battle Phase: Change all Defense Position monsters you control to face-up Attack Position. Both players take any battle damage involving this card.

Beast DARK Effect Monster 10 effect