Clockwork Wyrmling

Bound. The Clockwork Wyrmling is magically bound to an amulet. As long as the Wyrmling and its amulet are on the same plane of existence, the amulet's wearer can telepathically call the Wyrmling to travel to it, and the guardian knows the distance and direction to the amulet. If the Wyrmling is within 60 feet of the amulet's wearer, half of any damage the wearer takes (rounded up) is transferred to the guardian.

Consume fuel. Over the course of a long rest your Wyrmling may regain charges by consuming high quality charcoal. It regains 1d4+1 charges for each 1 GP of charcoal consumed.

The maxiumum amount of charges the Wyrmling can hold is 10. If the charges drop to 0 the Wyrmling is out of fuel and becomes inanimate until it is recharged with 2 gp worth of charcoal.

Flyby. The Clockwork Wyrmling doesn't provoke opportunity attacks when it flies out of an enemy's reach.

Regeneration. The Clockwork Wyrmling regains 5 hit points at the start of its turn if it has at least 1 hit point.

Immutable Form. The Wyrmling is immune to any spell or effect that would alter its form.

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

Hot Steam. The Clockwork Wyrmling exhales steam in a 10 foot cone. Each creature in said area must make a DC 14 Dexterity saving throw or take 7 ([roll]2d6[/roll]) fire damage on a failed save, or half as much damage on a successful save. This consumes 1 charge of fuel.

Hot Steam. The Clockwork Wyrmling exhales fire in a 15 foot cone. Each creature in said area must make a DC 15 Dexterity saving throw or take 17 ([roll]5d6[/roll]) fire damage on a failed save, or half as much damage on a successful save. This consumes 3 charges of fuel.

Enter the description for how bonus actions work for your monster here.

Shield. When a creature makes an attack against the wearer of the Wyrmling's amulet, the Wyrmling grants a +2 bonus to the wearer's AC if the Wyrmling is within 5 feet of the wearer.