This is a more tank build not so much for dps, but if you would like me to add a dps build as well I would be happy to.

Hey, Kilgameshx I like u build Alot but the thing i think it needs is some attack speed because Darius gives out alot of damage but most of the time it's slow you want someone who kills fast and move to a different champion and Own

A game that last forever you can expect to not hit much if everyone is scared of you and or did your team consist of a lot of AD? because if you have people countering you with armor you might want to drop atma's for last whisper. as for cool down you can switch movement speed in defence masteries to the CDR per level.

Hey kilgameshx I just tried out your guide. I'm not going to vote it down or up. I just had a game that lasted forever. We lost. My score with this guide was 13/13/13. It was frustrating cause my hits although strong was not enough in the team fights and/or 1v1 late game. I needed that extra damage output and just didn't have it. I'm used to playing a 21/9/0 mastery with same rune setup and I build tanky, so my damage output is there. When I hit my ult you know I just spoiled your day. When I hit my Q you are hurting...you know what I mean? The damage output was desperately needed from me in this game and I couldn't deliver the way I'm used to. Just a suggestion, maybe a tanky mastery would really need some cool-down items so u can spam your Q and W a lot more before "Apprehend" then W-(cripple) to Q or ULT, of coarse some Auto-attacks in between to keep the stacks up. I did enjoy how in this build the magic penetration actually made a deference early game. It gives Darius hemorrhage an intense bleed out, that was fun to watch.