Clockwork Wyvern

Wondrous item, rare (requires attunement)
  This limited edition clockwork wyvern comes with a fully-operational, miniature coal engine. Thanks to an intricate mix of steam-powered gears and pistons, the construct has lifelike movements and mannerisms.
  Combat. In combat, the clockwork wyvern shares your initiative count, but takes its turn immediately after yours. It can move and use its reaction on its own, but the only action it takes on its turn is the Dodge action, unless you take a bonus action on your turn to command it to take the action in its stat block or the Dash, Disengage, Help, Hide or Search action. The wyvern has a maximum of 10 charges; see the wyvern’s stat block for details on how to spend and recharge this resource.
  Death and Damage. The clockwork wyvern cannot regain hit points like other creatures. If the mending spell is cast on it, it regains 2d6 hit points. If it falls to 0 hit points, it loses all charges and becomes inert. Lightning or fire damage from a first level spell or higher can reinvigorate the wyvern, bringing it back to life with 0 charges.