Numerical Superiority: The Horde has advantage on attack rolls against creatures that are within 5 feet of at least 4 members of the Horde.
Turning Defiance: The Horde of has advantage on all saving throws to resist Turn Undead effects.
Multiattack: The Horde of Sacrificial Zombies makes 2 Thrashing Tentacles attacks if it has 75 or more hit points.
Thrashing Tentacles:
Swarm: The Horde consists of 10 Medium creatures, which share the same pool of hit points and all make a single saving throw. For each 15 damage the Horde takes, it loses a single creature. The Horde cannot regain hitpoints, or gain temporary hitpoints. Each creature in the Horde may move up to the Horde's speed, though members of the Horde must end their turn within 10 feet of another member if possible.
Single targe effects that impose a status effect instead inflict 15 unavoidable damage on a failed save, and have no effect on a successful save. Treat effects with fixed number of targets as a series of single target effects.
The Horde cannot take more than 15 damage per round from a given AOE effect (after resistances and saving throws), but the damage taken is multiplied by the number of models caught in the AOE.If the Horde makes a saving throw to end an ongoing effect, it does so with advantage.