Baelnor's Construct

Multiattack. Bealnor's Construct can make two attacks: once with each fist.

Pummel. Melee Weapon Attack: +4 to hit, reach 5 ft., 1 target. Hit: 8 (1d8 + 4) bludgeoning damage. 

Arcanite Shotgun. RangedWeapon Attack: +2 to hit, range 30/60 ft., 1 target. Hit: 7 (2d4 + 2) bludgeoning damage.

Opportunity Attack. Baelnor's Construct makes a single attack of opportunity with its fist for 1D8+4 bludgeoning damage.

Baelnor's Construct can take 3 legendary actions, choosing from the list of options below. Only one legendary action can be used at a time and only at the end of another creature's turn. Baelnor's Construct regains spent legendary actions at the start of its turn.

Shift Plates (Costs 1 Action). Baelnor's Construct can shift its plates to increase AC (+2) in a specific area, but becomes vulnerable from where plates were shifted from (-2 AC). 

Crawler Melt (Costs 2 Actions). On command, a Crawler, can move to Baelnor's Construct, suffering opportunity attacks if in range, and melt into it, healing 1D8 damage. 

Wallop (Cost 3 Actions). Baelnor's Construct begins to spin rapidly, then begins to move. All creatures in its path must make a dexterity saving throw, taking 2D6+4 bludgeoning damage on a failed save, and half as much on a success.