Alpha Zombie

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

Aggressive. As a bonus action, the creature can move up to its speed toward a hostile creature it can see.

Pack Tactics. The creature has advantage on an attack roll against a creature if at least one of the creature's allies is within 5 feet of the creature and the ally isn't incapacitated.

Greater Zombiism. Slow build up to extreme salivation and dehydration as well as when the onset of the disease is near an aversion to water or divine magics turns into a phobia of such things. Additionally, a feeling of resentment and mistrust that grows over time for other living beings. Each day while infected and not treated, the host loses ten maximum hit-points, additionally gaining a level of exhaustion every 48 hours. Upon falling to zero hit-points the infected instantly rises as a greater zombie.

Note. This creature was built assuming ruling for hit-points and wounds. Hit points act normally, and wounds represent actually getting hit. #Wounds = Constitution Score + #Hitdice. Wounds are caused by damage surpassing hit points and one wound per critical hit, where critical hits act normally to hit points. Normally, the infection would only afflict a wounded person.

Multiattack. The Alpha Zombie makes three attacks: two with its claws and one with its bite.

Claw. Melee Weapon Attack: ]+6 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 3) bludgeoning damage. The target must succeed on a DC 14 Strength or Dexterity saving throw be grappled (escape DC 14).

Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) piercing damage and must succeed on a DC 14 Constitution saving throw or suffer Greater Zombiism.