Combine Harvester

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

Magic Resistance. The Harvester has advantage on saving throws against spells and other magical effects.

Self Repairing. If the Harvester starts its turn with at least 1 hit point, it regains 5 hit points.  If it takes lightning damage, this ability does not function at the start of its next turn.

Manoeuvrability. Creatures being attacked by this have advantage on dodge rolls due to difficult manoeuvrability.

Multiattack. The Harvester can make two attacks

Speedy Combine (special attack) requires both attack slots to make: the combine roars forward at unimaginable speed  (80ft) gobbling up anyone in its path, they are then spat out the back incorporated into a bale of hay.

Melee Weapon Attack: +13 to hit, reach 10 ft either side. Any target in path. Hit: 16 (2d10 + 6) slashing damage, Roll 1d4 to determine how many limbs are free from the bail, Player must make a strength save of 16 to break loose or suffer 1/4 movement speed and disadvantage on dex rolls

Scythe. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 16 (2d6 + 6) slashing damage. On a critical hit apply the Combine effect.

Slam. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 19 (3d8 + 6) bludgeoning damage.

Oil Spray (Recharge 5–6). As a bonus action, the Harvester can release a spray of slick grease that covers the ground in a 10-foot square centred on a point within 30 feet turning it into difficult terrain. Each creature standing in the affected area must succeed on a DC 15 Dexterity saving throw or fall prone. A creature that enters the area or ends its turn there must also succeed on a Dexterity saving throw or fall prone.

Song of the harvest. charms a humanoid in 25ft range by playing a country folk song, anybody within 25 ft must make a Wisdom saving throw, and does so with advantage if you or your companions are fighting it.

If it fails the saving throw, it is charmed until the spell ends, your companions do anything harmful to you or you succeed on a wisdom throw without advantage. The charmed creature regards the combine at a familiar reliable old tool and spontaneously starts chewing a corn stalk while talking about growing weather. When the spell ends, the creature knows it was charmed by the combine.