Undead Fortitude. If damage reduces the zombie brute 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 brute drops to 1 hit point instead.

Slam. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 24 (4d8 + 6) bludgeoning damage.

Smash (Recharge 5–6). The zombie brute smashes the ground in front of it in a 10-foot square. Each creature in that area must make a DC16 Dexterity saving throw, taking 24 (4d8 + 6) bludgeoning damage and has their speed reduced by half until the end of their next turn on a failed save. On a successful save, the creature takes half as much damage and their speed isn't reduced.