User blog comment:Xeamnz/Most damage in a single turn/@comment-6881157-20140322004232

Jackknife "Aggressor" (4) + Grave Horn Dragon (2) + Red Dragon Knights "Song of Burning March" (1) + Dragonblade, Dragobrave (3) + Reckless Angerrrr!! (5)

Uh so that's 15.