I've played a lot of princes lately, and the nurgle one is the only one I would use out of a Tetrad. With the balesword he's truly a rockstar. The biggest problem is that they are able to be doubled out by
STR 10 so biomancy is pretty clutch. If you get endurance or iron arm on him, then the nurgle prince and balesword will rip through nearly anything.
This is very similar to what I've ran for my warphost, save for I took a forgehost instead of the prince and
LoC. I'd like to see how this works out for you.
Also the paradox won't keep you from peril'sing, which is still a 20% chance with 5 dice thrown. If you want the whole mathhammer behind the psychic phase, look
here.
Let me know how your games go!
Edit : By using Karios you can also get a 10+ on the warp storm table 55% of the time.
This article explains hows that's done.