Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 8 (2d6 + 2) piercing damage. This attack has disadvantage unless the target is grappled, incapacitated or restrained. The target must make a DC 12 Constitution save or be afflicted with the disease Zombie Rot.

Slam. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) bludgeoning damage. If this attack hits by 5 or more, the zombie can attempt to grapple the target as a bonus action and the target must make a DC 12 Constitution save or be afflicted with the disease Zombie Rot.

Undead Fortitude. If non-radiant damage reduces the zombie to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless it's from critical hit. On a success, the zombie drops to 1 hit point instead.

Horde of Fangs. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 16 (4d6 + 4) piercing damage. This attack has disadvantage unless the target is grappled, incapacitated or restrained. The target must make a DC 12 Constitution save or be afflicted with the disease Zombie Rot.

Press of Fists. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) bludgeoning damage. If this attack hits by 5 or more, the swarm can attempt to grapple the target and the target must make a DC 12 Constitution save or be afflicted with the disease Zombie Rot.

Undead Fortitude. When the swarm takes non-radiant damage, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless it's from a critical hit. On a success, that damage is halved, or the swarm drops to 1 hit point if it would be reduced to 0.

Swarm. The swarm can occupy another creature's space and vice versa, and can move through any opening large enough for a Medium undead. The swarm can't regain hit points or gain temporary hit points, flanks creatures whose space it's occupying, and has advantage on Strength ability checks. While at less than half of its maximum hit points, the swarm's attacks deal half damage. The swarm has advantage on saving throws against conditions and is immune to them unless imposed by an effect that affects the swarm's entire space.

Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) piercing damage. This attack has advantage if the target is grappled, incapacitated or restrained. The target must make a DC 13 Constitution save or be afflicted with the disease Zombie Rot.

Claw. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 8 (2d4 + 3) slashing damage. If this attack hits by 5 or more, the ghoul can attempt to grapple the target as a bonus action and the target must make a DC 13 Constitution save or be afflicted with the disease Zombie Rot.

Undead Fortitude. If non-radiant damage reduces the ghoul to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless it's from critical hit. On a success, the ghoul drops to 1 hit point instead.

Regeneration. The ghoul regains 5 hit points at the start of its turn. If the ghoul takes acid, fire, radiant or critical hit damage, this trait doesn't function at the start of its next turn. The ghoul dies only if it starts its turn with 0 hit points and doesn't regenerate.

Pounce. If the ghoul hits a creature with a Claw attack immediately after moving at least 15 feet straight towards it, the ghoul immediately makes a shove attempt against it. Then, if the target is prone, the ghoul can make an attack against it as a bonus action.

Stat blocks for the Minion and Swarm variants of the Plague Zombie have been included as samples.

Challenge Adjustment. Swarm variants of a creature per these changes can typically feature a +2 to +10 Challenge increase depending on the size of the Swarm vs the base creature (roughly +2 Challenge per size the Swarm is larger than the base creature), while Minion versions are typically about 1/4th the Challenge of the base creature. Consult the DMG and follow its calculation guidelines to arrive at more precise figures.

Swarms. To make a Swarm variant of a creature, set its size to whatever size you like, doubling its Hit Dice per size increase over the base creature (increasing its Hit Points per its new Hit Dice), give it the Swarm trait and Swarm Attack per the Plague Zombie Swarm sample and double the damage of all of its weapon attacks.

Minions. To make a Minion variant of a creature, simply set its Hit Points to 1, and its Threshold to its normal Hit Point total. A Minion that is critically hit will normally die instantly. Otherwise, when a Minion takes damage, unless that damage equals or exceeds its Threshold, that damage will be negated, and the Minion will instead gain the 'Bloodied' condition until it would regain hit points or it gains temporary hit points. A Minion with the Bloodied condition will have its hit points reduced to 0 when it takes any damage.

When making a large, cinematic horde of zombies, it's usually best to do this in two ways, utilizing swarms and/or many minion versions of a creature.

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 8 (2d6 + 2) piercing damage. This attack has disadvantage unless the target is grappled, incapacitated or restrained. The target must make a DC 12 Constitution save or be afflicted with the disease Zombie Rot.

Slam. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) bludgeoning damage. If this attack hits by 5 or more, the zombie can attempt to grapple the target as a bonus action and the target must make a DC 12 Constitution save or be afflicted with the disease Zombie Rot.

Undead Fortitude. If non-radiant damage reduces the zombie to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless it's from critical hit. On a success, the zombie drops to 1 hit point instead.

Zombie Rot

Summary: A magical plague that can only be cured by magical healing. Left untreated, it withers and kills all life it encounters, reanimating it into hungry, shambling undead.

Disease Transmission: When a creature is bitten by a creature that carries the disease, or when a source of contamination (usually offal, bodily fluids or biological waste) is ingested or otherwise exposed to that creature's digestive, respiratory or circulatory system, the creature must succeed on a DC 12 Constitution exposure saving throw or become infected. Especially potent carriers or disease vectors may feature higher DCs at the DM's discretion.

Incubation: It takes 1d4 days for Zombie Rot's symptoms to manifest in an infected creature, minus 1 day for each extra failed exposure save, and every 5 points the creature failed an exposure saving throw by. It is a carrier during this time with exposure DC 12. If the number of days are reduced to 0 in this way, the disease manifests immediately.

Manifestation: When the disease manifests, the infected creature immediately loses 2d4 Hit Dice, and can't regain Hit Dice or reduce its exhaustion level by any means except that stated in this disease profile. Whenever the infected would lose one or more Hit Dice from this disease when it has none remaining, it gains a level of exhaustion instead. While it has no Hit Dice, the infected can't regain hit points and counts as being poisoned, ignoring immunity to the poisoned condition.

Disease Progression: At the end of each long rest, the infected must make a DC 14 Constitution progression saving throw. This saving throw must be made immediately on each failed exposure save while the disease is manifest, with no benefit for success.

Save Failure: The infected loses 1d4 Hit Dice, plus an additional 1d4 per 5 points it failed this saving throw by, and the progression save DC increases by +1 as the infection takes hold. During the incubation period, no Hit Dice are lost.

Save Success: Unless the infected has received magical healing since the end of its last long rest and has adequate food and drink, a save success does nothing. Otherwise, the progression saving throw's DC decreases by 1 to a minimum of DC 14. Further, the infected's exhaustion level is reduced by one if it has any, otherwise it regains 1d4 Hit Dice. An infected that has regained all Hit Dice is cured of the disease. During the incubation period, the infected must succeed on three of these saving throws consecutively to be cured of the disease.

Special: A creature that dies while infected with this disease reanimates as a plague zombie of the appropriate size after 1d4 rounds.

Non-Artifact effects and spells that would cure this disease do not automatically succeed; instead they count as magical healing and permit the infected to immediately make a progression saving throw as if it had taken a long rest, with no penalty for failure. For each level such a spell exceeds the 5th, it permits an additional saving throw in this way.

A remove curse spell cast on the infected counts as an instance of magical healing for the purposes of this disease.

Plague Zombie

Dessicated victims of Zombie Rot, these unfortunates are reduced to tireless, shambling husks ever hungering for uninfected flesh. Plague Zombies lack any sort of true intelligence or purpose save satiation of their bottomless hunger, moving with awkward clumsiness towards the nearest prospective meal. Though their senses are largely diminished in undeath, they're nonetheless attracted to sound and light, known to fall upon camps with open flames to devour their inhabitants.

Nearly mindless, and knowing no fear, a Plague Zombie will always take the most direct route to its prey no matter the danger involved, utterly uncomprehending of obstacles.

Once the disease has achieved critical mass within them, or they've devoured enough victims, a Plague Zombie undergoes a strange metamorphosis into a vastly more dangerous creature: the Plague Ghoul. The profile featured assumes a Zombie naked or clad in regular clothing or rags; adjust AC values as needed in the event a zombie happens to be wearing armor.

Plague Zombies tend to focus on devouring the downed and helpless, preferring them to other equally distant prey. A Plague Zombie that kills and feasts on a living creature will metamorph into a Plague Ghoul within 1d4 rounds, minutes, hours or days (roll a d4 to determine which). For each additional creature feasted on in this way, this duration is reduced by 1 unit of the same amount of time. If this duration is reduced to 0, the Plague Zombie immediately transforms into a Plague Ghoul in a horrific metamorphosis.

Plague Ghoul

Fast, dexterous and deadly, Plague Ghouls are the more durable and intelligent evolutions of their zombie predecessors, rotted skin sloughing off to give way to hardened blood red hyper-musculature. Where once existed hands, there are now sharp, serrated claws, with wicked talons up to a foot long. They feature significantly heightened strength and agility, readily able to run down victims that would have been able to evade a standard zombie without effort.

Though they know no fear and are extremely aggressive, a modicum of intellect enables them to recognize and avoid the most deadly, obvious and dangerous obstacles en route to their prey, navigate stairs and most doors, and engage in a bare vestige of tactics, preferring to attack those that inflict the most grevious wounds. The disease has taken such hold that the ghouls now regenerate even the most serious wounds given enough time, with only acid, fire, scouring radiance, or a decapitation serving to halt an otherwise inevitable recovery.

Like Plague Zombies, Plague Ghouls evolve and change, gaining adaptations over time and with each victim slain. You may choose to give a plague ghoul one or more such traits selectively or at random. For every 2 extra traits that add attacks, impose conditions or increase accuracy, damage, durability or DCs, incrementing the ghoul's Challenge by 1 is usually advisible. Traits they can gain are as follows: