From Halopedia, the Halo wiki
The Ironclad is a variant of the Blisterback. It is equipped with more heavier armor on the front and its legs.
The Ironclad is a unit available for play in the Blitz and Blitz Firefight modes of Halo Wars 2. It is available to players playing as Pavium. The Ironclad Blisterback Blitz card has the following attributes;
The Ironclad is classed as a mobile artillery that performs well against infantry, and vehicles not against aircraft unless converted to air mode. If this unit is in fatal/sever condition, if this unit is guarding another unit while it's be healed, this unit will also receive healing regardless if the unit it's guarding is full health or not.
List of appearances