Adamantine slug

The Adamantine slug in it's compact form it runs up and down the horseman's body secreting a mucus that hardens over time and turns whatever armor set The horseman is wearing into an adamantine set of armor on top of the additional affects the armor may have.

compact form stats.

Size: tiny

Hp: 200

Ac: 20

Speed: 5ft climb

Colossal form stats

Size: colossal

Hp: 400

Ac: 18

Speed: 20ft walking

(acidic siege attack)  

Range: 5ft

To hit: +8

Damage 8d8 acid double the damage if it's a structure.