Forum:Eff of the Mist valley Apex Avian X Field Dark World

Then an Opponent activates the field dark world, I can turn eff the Mist Valley Apex Avian, to negate the activation of eff to increase by 300 atk all Fiend monster, rising mist valley a card?

--201.51.150.38 (talk) 22:19, February 2, 2013 (UTC)