I'd love if it wasn't an active skill. Think : reducing attack so creature with nice abilities aren't affected by shields?
For the cost i almost think this card is UP and the cost should be reduced. I mean lightning kills most creatures right then and there and costs 1 upgraded. and this form of cc is extremely slow. shrieker 8+7+6+5+4+3+2+1=36 damage and 8 turns before it finally gets 0 attack. granted shrieker isnt a typical card, the time it takes to finally be decently effective is a nerf of its own and the cost should be reduced