I've been using a Nurgle Warptime DP in my last few games but I'm yet to have him alive by turn three.............

Am i sticking him out too early, shoul I be hiding hrm for the first couple of turns..........

How do you guys use them ????????????

Present other targets in support of the prince, a raider full of termies poses quite a tactical dillemma. It is most of the time a question of viable targets versus your opponents fear of the big nasties. Some of my foes go out of their way to slaughter my sternguard vets so what do i do, i take a second unit just to watch the look on their face, after a whole turns worth of fire spent in eradicating the hellfire boltgun brigade, a second unit just debuses from their rhino and does the business.

Also try to eliminate the units that can batter your prince at range. He, of course, may still get whupped in combat but if you charge Lysander expect to get hammered (he he he!).....

He may not be alive by turn 3 but what does it take to kill him? If its a lot then that fire power is not hitting the rest of your army.
Are you taking wings? As this will get you into combat earlier.
As The Colonel said other viable targets will allow him to survive, I take a summoned Greater Demon, they make a great tag team!

So far he's got killed by a unit of shining spears ( taking 4 with him )

Blasted off the table by a unit of Big Shoota's and had a new one ripped him by a unit of Nob Bikers with 3 PF in it !!!

I use a Tzeentch DP with Warptime and Wind of Chaos. I have a habit of leaving him out there all alone. IMHO, they need support to draw fire and help with setting up assaults. Also realizing that a 3+/4++ Save doesn't make them invincible would probabyl help.

Ogreguts is the way I play them.
I don't take the 210 point CC monster.. I take 2 that are fast and that will do enough damage.. they draw enough fire to save my whole army for X turns..and as a SIDE BENEFIT might be awesome in CC. 260 points that gives me 1240 of free shots (heck add the lashs and your still only 100 more than some people build a single prince)
(but everyone seems to use them differently in tacticas where i've said I use them as effective meatshields/firemagnets, generally the majority plank of wood response is that I either use no terrain or no tactics..meh)

Best way to use a Demon Prince is to get him drunk, take him back to his place, spend the night in bed and leave before he wakes without giving him your number, just a thanks for being a fook bud note.

Boy will he feel used...

I run a Nurgle and a Slaanesh one, both with Wings and Warptime. For unknown reasons the Nurgle one always seems to get slapped down with little effort in CC....

I usually move squads forward in Rhinos and hold the DPs behind there as a mobile counter-attack.

Nurgle guys a solid line backer, but not the most offensive in my opinion. Have used the sheesy 2 slaanesh princes with whip. Great in tandem with hvy weapons for creaming units. Pull units into charge range and clobber them with fighty units, or pull into range of obliterators and/or battle cannons. Wings are of course obligatory for the tactical edge.

Key thing is remember that as hard as he sounds the earlier edition psychology of 'he's invincible and will kill anything' no longer holds true. Yes he's hard. Yes he's killy. Sadly the average marine codex captain outdoes him these days. Use him carefully, commit him to the right fights and look for the 'trick' in the build you take to maximise impact.