The slow encroachment of disease can lead to victory.
Chaos cards: All Things Decay x2, The Final Rotting x3, A Great Foul Consumption x3, Influenza x4, Plague Aura x4, Plague Touch x3, Rain of Pus x3, The Stench of Death x2; total deck cost: 27.
Expansion Chaos cards: Choking Stench x4, Creeping Death x4, Festering Fever x3, Filth x3, Nurgle's Quest x1, Quicken Decay x3, Ultimate Plague x2, Virulent Outbreak x4; total deck cost: 28
Upgrades: Great Unclean One, Lepers, Plaguebearers Power of Pestilence, Provender of Ruin
Expansion Upgrades: Cavalcade of Decay, Great Unclean One, Infested Colony, Lepers, Plaguebearers
Figures: 1 Great Unclean One, 5 Plaguebearer Warriors, 6 Leper Cultists
Dial: Score 3 VP; Remove 1 Corruption; Upgrade Card; Score 3 VP; Upgrade Card; Remove 2 Corruption; Upgrade Card; Score 3 VP; Remove 2 Corruption; Nurgle Victory!
To most Chaos in the Old World (CitOW) players, Nurgle is the polar opposite of Khorne in terms of a path to victory. Whereas Khorne almost always wins via the dial, Nurgle almost always wins via victory points. In a way, it's kind of appropriate that the two oldest gods and, thus, the first two in turn order (Age before beauty, yo) should be so radically different, even if their chief rivals in the lore are the two younger ones (Slaanesh and Tzeentch, respectively.) Nurgle is in it for the long con. He wants to stretch the game out, delaying the advance of others until he can cover the Old World in a tide of filth and disease. Since the latter often does take longer than a berzerker's axe to signal one's end that, too, is appropriate. But that tendency has also often tagged Nurgle as the most difficult god to win with. Since everyone knows that Nurgle has the longest dial and that the desired regions of the Plague Lord will never vary in the way that the others' do, it often feels as if Nurgle players have a large target painted on their slimy backs and are there to be picked on, especially by Khorne and his rampaging Bloodletters. But there's an insidious power in the green horde. Everything decays to chaos(!) and entropy and if you can stay in the game for a few rounds, securing what dial advancement tokens that you can achieve and scoring as much Domination as possible before regions begin falling into ruin, there will come a moment when the disease becomes inevitable and you can surge forward before your opponents realize what has happened. As a personal anecdote, the first two times we played CitOW we played with three players. My friend, Nathan, and I were accustomed to winning board games and 40K/Fantasy games on the regular. Our friend, Rob, was accustomed to losing those games. But Rob won both of our CitOW games and did so with Papa Nurgle.
Admittedly and in contrast to Khorne, it's probably even less likely for Nurgle to win via dial ticks, especially in 4- and 5-player games, as the traffic will often just be too thick in the regions that Nurgle wants to control; not only because Noble, Warpstone, and Skaven tokens might end up there, but because the Populous regions are the highest in Conquest value on the board. Those are the best targets, points-wise, for everyone, which means that competition will be fierce. However, in the same manner as Khorne, taking advantage of Domination and Ruination scores in the outer regions while still trying to advance your dial in at least one of the Populous ones can lead Nurgle players to a points total that will turn out to be threatening after a couple rounds. Then it's a matter of focusing on a couple of those big targets with your greater number of figures and overwhelming the opposition to close the game out. Difficult? Yes. Impossible? Far from it. Remember, too, that with Warpstone counting as Corruption and Nobles raising Conquest value, you can get faster and better value from some of those smaller regions if you can leave Khorne to muck about in the Populous regions with the other players, while you just have to outnumber one opponent in The Border Princes or somewhere similar for a couple rounds. However, one steeper hill that Nurgle does have in comparison to the other gods is that it takes three dial ticks to receive an upgrade, while all the rest only take two. So, it's certainly a regular feature that you're often going to be facing enhanced opposition for a round before you can start pushing back at the same level. But, again, slow and steady wins the race of death.
Figures and Upgrades-
There's nothing particularly remarkable about any of Nurgle's figures, as they're pretty much middle-of-the-road, stats-wise, across the board. That includes the number of figures. With a total of 12 and 6 Cultists, that places Nurgle pretty squarely in the "average" level as far as the five gods go. But something that helps with that is that it's the only god with Warriors that only cost 1, so it's easier for Nurgle to put a significant number of bodies on the board. That's a lot of bodies to help accumulate Domination. Pull off Domination in Kislev and Brettonia in one round and you've just scored over 10% of your total needed to win just by having (ahem) dudes on the map. Of course, part of Domination is Chaos card value, as well. There's an assumption out there that Nurgle's cards cost too much for what they do, but the actual total cost of the base deck is 27. Khorne, often heralded as having the cheapest cards for effect, has a total cost of 26. It's just a different mindset that has to be used with the Plague Lord. Unlike Khorne, your figures aren't really present to play an active role. They're present often simply to be there and further your longer-term goals, although the upgrade to Plaguebearers can impact that somewhat. Unlike Khorne (again), the most prominent upgrade for Nurgle may, indeed, be the one for Lepers. Being able to take actions that cost 0 Power is almost always an advantage for any god, since it allows you to delay while being able to reorient toward your actual target (A frequent strategy of Tzeentch players.) 0-cost Lepers lets you make a chain away from a hotspot and toward another Populous region that you may be able to Dominate and then ruin without much interference. However, it does have to be to a region where you're not present at all, which can limit its effectiveness, since you generally want to pack regions with dudes so that some survive the inevitable attacks. The Plaguebearers upgrade also makes you a less tempting target for opponents, since they'll often be losing their more tenuous grip on a region if they choose to target you in battle. However, since they can pick their targets, this is more a tool of dissuasion. The Great Unclean One is also a fairly good value for what it accomplishes, especially with the upgrade, since you can add two Corruption plus a 3-attack unit wherever he goes, not only often ensuring Ruination with the most Corruption but smashing other Cultists out of the neighborhood. Provender of Ruin can add up to almost 1/3 of your required total if you correctly play the long game to 5 ruined regions and even just getting the additional 6 points for the first couple may be enough to snare you the win. I have found Power of Pestilence to be somewhat less urgent, overall, since the costs for Nurgle aren't as onerous as often thought, so you're often better suited to enhancing your proliferation of dudes than taking yet another long-term benefit.
The expansion upgrades aren't as reorienting as one might expect them to be, since they're largely about accelerating the pace of the game, as much as they are getting more dial ticks for Nurgle. Certainly, having four of the five increasing the amount of Corruption that Nurgle can lay down is a way to pull out a win faster than any other god can finish their dial. It also lends weight in the direction of Nurgle actually being able to achieve two ticks per round, since there will be Corruption raining all over the place if others kill your Plaguebearers or when your Great Unclean One kills enemies or simply by doubling the Corruption power of every lone Leper that you have on the board (e.g. One Leper places one Corruption and, therefore, places two with the upgrade and scores a token.) But that also means that regions will become ruined much faster, bringing about the end of the game that you've hopefully established a point lead in. This is where the oft-bemoaned dial ticks of "Remove X Corruption" can really come into play, as you delay to the appropriate moment for you to get the higher Ruination score. But the most game-changing of the upgrades is clearly Cavalcade of Decay, since it turns ANY region with five or more Cultists of any of the gods into a Populous region. That alone can often take the target off your back, even if the original Populous regions are still the most inhabited because of their greater Conquest scores. If most of the Warpstone is in the outer regions, then it's easy to turn The Badlands into a Populous region by contesting the area with Tzeentch, for example.
Card play is extremely important for all of the gods, but there are a couple for which it's one step beyond. Nurgle is one of those gods. Since Nurgle is playing the long con, you really need to set up repeated combos in those high Conquest value regions. One way to do that is via Plague Aura and Influenza. Both of them will enable Domination with fewer figures required, although Aura will require a couple rounds of setup while Influenza can be played right away. The latter will also attract other players, since reducing Resistance means that any player can have access to easy Domination as long as they come out on top. The Stench of Death and A Great Foul Consumption are closer cards. (Don't try to "always be closing" with Nurgle.) Those are the ones you want to play when Ruination is happening and you're going to end up with a marked lead in Corruption tokens, often enabled by those cards. Considering their cost (3 and 2, respectively), it often means that you'll be getting the Domination score, as well, so they can combine for a huge burst of points in the Populous regions. The Final Rotting and Plague Touch are cards for when you're struggling for position. Reducing the defense of annoying Daemonettes, Rat Ogres, and Horrors makes them more enticing targets for Khorne, which means they may not be interested in sticking around. But Final Rotting also makes an area less interesting for Khorne, since they'll have to re-summon those Bloodletters that your Corruption kills. It's a half-measure, since they'll still get the advancement tokens, but it's still a measure. Of course, the real deterrent to Khorne is usually Rain of Pus, since having to expend two hits to remove one Leper isn't normally what the Blood God wants to spend its time doing. The last card, All Things Decay, is often of questionable value, since the expenditure of a Power point to remove one Corruption seems inefficient. It's a very situational card that can set up some great combos (giving you a one Corruption edge for Ruination,etc.) but has to have circumstances that really work for it. Also, keep in mind that Aura and Stench both have magic symbols, making them attractive for Tzeentch.
Expansion Chaos cards:
It's fair to say that the expansion deck is much more aggressive and direct than the base game deck. Your card play is going to be much more pointed. Instead of the slow, insidious progress of the disease, it can feel more like the common cold turned to pneumonia overnight. The most obvious are Festering Fever and Virulent Outbreak, since the former immediately gets you an advancement token when you Dominate and the latter functions like Cavalcade but without needing Cultists. In both cases, the cards are designed to accelerate Nurgle's dial ticks, which was one of the emphases of the expansion for the Plague Lord. But the rest of the cards still largely stay in theme with Nurgle's original play. Creeping Death and Filth accelerate your Corruption. Choking Stench inhibits the ability of opponents to remove your Lepers and Quicken Decay tests the will of others to invade your space, since they'll be giving you VPs every time they enter or exit the region. Ultimate Plague is a Domination key, since you'll keep a card space and have an automatic value of 3 every time you can place Corruption. Again, the theme of Nurgle is still the long con and the expansion doesn't veer radically from that, even with the changes to dial speed. But the most interesting card is the only one-off in the deck: Nurgle's Quest. It's an extraordinarily steep cost, at 4 Power, but if you know that your next dial tick could have real impact on the current round, it gives you the benefit right away, in that very Summoning Phase. It's definitely a card for the veteran CitOW player and I've personally never seen it pay off in significant fashion, but the potential is there. Again, keep in mind that Fever, Filth, and Quest all carry magic symbols, as well.
Nurgle is a god that will certainly benefit from the social engineering that should be taking place in any CitOW game in the first place. Pointing out how far behind you are on the dials and how Khorne may be picking on you, especially in the direction of players who may not be reading the board as well as you and are missing the ominous green tide across its center, is all perfectly fair game. Nurgle should be looking for trigger points after the first couple rounds. By that time, you should've been able to set up enough regions to tumble quickly and fire you ahead on the VP track, making you leap from whining straggler to ominous leader. It's at that point that you might be grabbing your first upgrade, as well, which means you'll have been building into an awareness of how your opponents are playing and should be able to make the right choice that suits the particular circumstances of the struggle. You want to be the miasma that's in the background while everyone else is distracting themselves with more dynamic actions in the early game and competing directly with each other while you just continue to grow. In that respect, Be Like Rob. In the end, everyone will succumb to the disease.