I was able to play a few friendly matches this past week while on vacation bumping my 1850 point KDA up to 2000 points. I had to drop three Bloodletters from my two troop choices so I could afford all the goodies/upgrades I wanted. Here is the build:
Daemon Prince (Codex Daemons)
Mark of Nurgle*
Cloud of Flies
*Those of you that know me understand that I have a great love for all things Nurgle! So this is my first non Khorne unit so the army is no longer truly KDA with it's inclusion but I really like the Nurgle daemon prince a lot better than his Khornate counterpart and have modeled the prince as a 'counts as' Khorne daemon prince. To me the Nurgle prince is the best choice and I didn't give him any psychic powers in an attempt to stick as closely possible to the original theme. T6, always wounding on 2+ plus Cloud of Flies are both of great value in terms of performance. My prince got into close combat with a Nurgle Prince from the CSM codex and beat the living snot out of it, the CSM prince had warp time too.
Versus meched up armies it's great to have another flying monstrous creature to tank hunt besides the greater daemon (Bloodthirster). Once you start popping a few transports it certainly makes it a lot easier to swing the battle in your favor. I will always use mygreater daemon to destroy landraiders, it's almost a sure thing unless he is hitting on sixes, so even if he dies the next turn it's worth the trade. The daemon prince is great for taking out chimeras and rhinos. Using the flying monsters to take out tanks means I can focus the two Soul Grinders on dropping pieplates of death. It's a strong combination.