Calukul

Built for Success. Calukul can add a d4 to one attack roll, ability check, or saving throw Calukul makes, and Calukul can do so after seeing the d20 roll but before the effects of the roll are resolved. Calukul can use this trait a number of times equal to Calukul's proficiency bonus, and Calukul regains all expended uses when Calukul finishes a long rest.

Healing Machine. If the mending spell is cast on Calukul, Calukul can spend a Hit Die, roll it, and regain a number of hit points equal to the roll plus Calukul's Constitution modifier (minimum of 1 hit point).

Mechanical Nature. Calukul has resistance to poison damage and immunity to disease, and Calukul has advantage on saving throws against being paralyzed or poisoned. Calukul doesn't need to eat, drink, or breathe.

In addition, Calukul's creator designed them to benefit from several spells that preserve life but that normally don’t affect Constructs: cure wounds, healing word, mass cure wounds, mass healing word, and spare the dying.

Spellcasting. Calukul is a 1-level spellcaster. Its spellcasting ability is wisdom (spell save DC 12, +2 to hit with spell attacks). Calukul has following spells prepared:
Cantrips (at will): Guidance, Mending
1st level (2 slots): Searing Smite

Mace. Melee Weapon Attack: +4 to hit, reach 5 ft., 1 target. Hit: 5 (1d6 + 2) bludgeoning damage. 

Light Crossbow. Ranged Weapon Attack: +1 to hit, range 80/320 ft., 1 target. Hit: 3 (1d8 - 1) piercing damage.