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.

Bottom Treader. The zombie cannot swim, and it sinks to the bottom of any body of water. It takes no penalties to its movement or attacks underwater. It is immune to the effects of being underwater at a depth greater than 100 feet.

Net. Melee or Ranged Weapon Attack: +4 to hit, reach 5 ft. or range 5/15 ft., one target. Hit: 3 (1d6) cold damage, and the target is restrained if it’s Large or smaller. On subsequent turns, a creature can use its action to make a DC 10 Strength check to free itself or a creature within its reach. Dealing 5 slashing damage to the net, which has an AC of 10, also destroys it.

Dagger. Melee or Ranged Weapon Attack: +4 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 4 (1d4+2) piercing damage plus 3 (1d6) cold damage.