Thanks, Brother Ryld. Just 1 additional useful insight, from having used my Death Guard list vs. a Chaos Daemons list recently.
Disclaimer - I noticed you listed your miniatures collection, so you probably have your Daemon Princes already painted, and you're probably staying very true to WYSIWYG. That's what I'd do too, it's the honourable thing to do. But I should mention this in case you don't already use it, while you're still testing the list.
Obviously, there's overlap between the Death Guard and Chaos Daemons codices, so I noted minor yet significant differences, and here's one such.
The Death Guard have a Warlord Trait and Relic combination that's particularly powerful. The Warlord Trait is Revoltingly Resilient, which buffs a Nurgle Daemon Prince's "feel no pain" save from 5+ to 4+. The Relic is the Suppurating Plate, known in my meta as "the 2+ armour that literally gives cancer" (not making light of cancer, that's just this meme-like name people gave it), which not only buffs the armour save from 3+ to 2+,
but also has a 4+ change of dealing mortal wounds in melee when a save...any save...is made (so that can be the actual armour save or against power AP weapons the invuln save, THEN the "feel no pain" save). This combination dramatically increases a Daemon Prince's resilience as well as deadliness.
3 Daemon Princes + 3 Nurglings is basically a Battalion Detachment that qualifies as either Death Guard or Chaos Daemons codices, so this combination may be available to you. Just letting you know rather than being in a "why didn't anyone tell me about this" situation, especially with the stake of a tournament in mind.
Edited by N1SB, 18 April 2018 - 10:11 AM.