If I use Shred off Giratina on my opponents Sigilyph, Do I knock out Sigilyph? Since Sigilyph says prevent all effects of attacks and Shred's effect allows Giratina attack through effects on the defending Pokemon (i.e. Abilities, Tools, etc...) I, and my friends, are kinda confused on the ruling. A few say Giratina does knock it out, but we would like a more definite answer. Thank you 
