AD Viktor is not troll and is really viable. Viktor's Q has a 100%AD scaling.Think about this,upgrade the Siphon Power(Q) makes u gain movement speed after u land your Q.Since u have a decent amount of AD u can deal massive damage and use the bonus movement speed to kite tanks.Conversely,if ur chasing your enemy,u can place a Gravity Field(W) to get closer and use Q to infinity chase.In this build,I think the Trinity Force is the essential item,first,Trinity Force plus Infinity Edge and a Essence Reaver will reach 40%CDR. In addition,the passive from Sheen and Phage work tremendously on Viktor. After Trinity Force,just build flat AD. Armor pen is useless on Viktor so **** it.Don't build Youmuu and Duskblade.