Silver Plant. The ZXY isn't actually that durable, they're made of a self regenerating metal infused with a rare silver plant from their home planet. and heals 2 hp at the start of every turn.

Spellcasting. The ZXY is a 3-level spellcaster. Its spellcasting ability is dex 10, +6 to hit with spell attacks. The ZXY has following spells prepared:

Cantrips (at will): continual flame, inflict wounds
1st level : thunderous smite, create or destroy water

Persistence.  In order to be defeated the amount of damage I finishing blow must match the creature's remaining hit points. (for example: 5hp - 5 damage = 0) any extra damage dealt will be added to it's hit points. (for example if hit has 5 hit points and takes 8 damage then it takes the five damage but heals back the extra 3)

Status report. Alerts 2 more ZXY of your location which appears after 5 of the ZXY's turns  if ZXY hasn't been defeated.

Iron blow. Melee Weapon Attack: +5 to hit, reach 5 ft., 1 target. Hit:  3d8 + 2 [bludgeoning] damage.

.50 BMG. Ranged weapon attack:  +5 to hit, reach 500ft., 1 target. Hit: 4d8 [piercing] damage. When a target is hit, they take an extra 1d4 fire damage at the start of each of their turns. The target or another creature can use their action to extinguish the flames. On a hit, the target takes an extra 1d6 fire damage, and any creatures within 5 feet of the target takes 1d4 fire damage.

.9mm. Ranged weapon attack:  +5 to hit, reach 50ft., one target. Hit:`2d8 [piercing] damage.

Cowardice. It attempts to flee, (Dex saving throw of 10+ if player chooses to chase)

Quickdraw.  if your opponent's hit points are at five or lower after an attack, then you can use a reaction to deal 3d6 radiant damage to another enemy if possible.