Black Plaguehearts only appear after day 6 if you started a brand new community, and after day 2 if you transferred the same community to a new map. When the curveball becomes active, one random plague heart around the map becomes the black heart. Its radius of control increases massively (roughly 2x) and all dormant plague hearts within this radius will awaken, bringing the usual host of trouble associated with that.

When you first encounter a black plagueheart, you'll see this page in your curveballs tab in the map menu screen. This will tell you a bit of information about what the plagueheart will do, but not everything.

When this curveball becomes active, zombies in the area have a very high chance to become black plague zombies, and all future plague zombies will be black plague zombies. There are two forms these zombies can take:

• Zombies are stronger: "Zombies around the Black Heart are more resilient to melee attacks and have improved senses.
  
• Plague Zombies are Stronger: "Plague Zombies near the Black Heart are immune to fire, move faster and are highly infectious."

Additionally, the area of effect for this plagueheart will increase over time to a maximum diameter of 1216m. The area will also cause one of two effects. These effects are not distinctly named, but have unique effects:

• The Black Heart (A, Thick Miasma): "The Black Heart is extremely resistant to attacks and its Miasma will drain fuel, but it has a weakness."
  
  • If your heart has Thick Miasma, your vehicle's fuel efficiency will tank, such that you can't travel very far in a vehicle before your vehicle runs out of gas. In U34, this was only 100 meters or so, but the fuel drain rate has been nerfed so it should be larger as of U36.
• The Black Heart (B, Toxic Miasma): "The Black Heart is extremely resistant to attacks and its Miasma is toxic, but it has a weakness."
  
  • If your heart has Toxic Miasma, it will slowly drain your health over time, down to a low amount. In U34, this was down to a sliver, but it has been nerfed slightly to allow you more health as of U36.

The heart itself will have double the health of a normal plagueheart for your difficulty, and take ~7x less damage from all sources except for one. This damage source only deals half damage to the black heart as compared to a standard plague heart. However, you won't be told what source this is until you complete the optional objective "Discover a Weakness". Once you have completed that objective, the enclave will tell you what damage type you need to use to be most effective.

Ideally you want an outpost that has at least one of the following:

• In or near the radius of the plagueheart
  
• Close to a high-traffic route for both you and zombies
  
• Near enough to the edge of the Plague Heart's new expanded territory that you can drive up to the edge.

Ideally you want an outpost similar to the radio outpost or ammo outpost in this image, as they're close enough to allow you to resupply easily.

Once you've set up your outpost in this way, ensure that the outpost is heavily protected by activating the Incendiary mines defense on the outpost you wish to enter and exit this territory through. That way you can run back to a safe area if you get aggressively overwhelmed by the enhanced plague zombies and have a way to deal with infesting hordes as they come from the awakened plague hearts within the black heart's domain.

While in the safe zone of your outpost with incendiary mines active, you can easily farm for black plague samples. These special quest items are what you'll use to discover the plagueheart's weakness. Collect 5 samples and deliver them to the science enclave spawned by the curveball and in 24 hours in game you'll discover the heart's weakness. This enclave will leave as soon as you deliver the samples, and as far as I know none of them are recruitable.

Additionally, it's not worth trying to stock up on the black plague samples or try to get them over multiple game sessions. If you log out with the samples in your inventory they disappear to prevent using the samples on other plague hearts, and you can only collect these samples in stacks of 5 as opposed to the infinite stack size of standard plague samples. The samples also cannot be stored in the supply locker, so your best bet is running them over to the enclave as soon as you get the needed 5 samples.

Now that you know the weakness of the heart, get a follower that's pretty powerful and give them enough gear to stay alive and carry supplies for you. There's a guide by State of Decay Science that's floating around the internet which lists the damage values of different calibers of ammunition, thrown explosives, radio-controlled explosives, and how attachments affect those values. Using this could help you take down the plague heart faster. (I'm having trouble inserting links or adding images to this guide, will do as soon as I'm able)

Regardless of the heart's weakness, you want your best survivors to take this heart out, and you want to take them in and out mostly alive. Pack in plenty of stimulants, painkillers, energy drinks, and a few plague cures if you feel like you need it. There's gonna be a lot of running from the plague zombies, and a lot of walking to the heart if you have a thick miasma.

It also couldn't hurt to get a scentblock on your follower and main survivor when you're entering plague territory, and regardless of weakness smoke grenades can be really helpful for the first few volleys of shots in a ranged weakness heart takedown. If the heart is weak to melee weapons, be sure to drop the smoke grenade far enough away from the heart that you can back up and still be safe from zombies when the heart starts spewing gunk on you.

If you have an outpost that offers artillery or have a command center at level 3 with computer knowledge, getting an artillery or drone strike off to begin this fight wouldn't be the worst idea, especially if it's a heart weak to explosives.

While this damage won't necessarily help take down the plague heart unless it is weak to explosive damage, it can still help clear out the zombies around the heart for a little bit, giving you a window to set up smoke grenades and scentblocks to get you closer to the heart.

Now that you've appropriately set up to take out the heart, give it all of your damage. Take your melee weapon of choice and slam into it while managing stamina with energy drinks and stimulants. Take your best gun and unload as many mags as you can into it. Throw a road flare and bloater grenade through a window at it, or otherwise set up explosives to take it out. Regardless, you want to get as much damage into the plague heart as possible according to it's weakness. The plagueheart never enters a dormant state, and will constantly remain awakened as long as its alive, so just taking it out as fast as possible is the best option you have. Dealing damage to the heart will only increase the frequency of infestations and aggressiveness of plague zombies.

Keep those smokes up, keep the damage flowing, and most importantly, keep you and your follower alive as long as possible. If you're running out of supplies to keep your health high and plague infection low, return to the outpost and heal up.

Repeat steps 2-4 over and over again as needed, using scent block and smokes to create an opportunity to escape to your outpost if you absolutely need it. Repeat this until the black plagueheart is no more!

Thank you again to Lemonidas of Sourta for the rough outline of this guide, and to groups like State of Decay Science for conducting tests to see what works the best against this threat. Thank you for reading, and if you enjoyed I'd greatly appreciate a like, favorite, or award at your discretion!