An Imperial Knight Paladin excels in engagements, where its Chainsword and Shock Lance will make short work of most targets. It is also armed with a Battlecannon for long range support.
The Ordinatus Mars is a gigantic mobile weapon platform employed by the Adeptus Mechanicus. Its Sonic Disruption Cannon has huge range, and will destroy absolutely anything under multiple blast templates. It has Void Shields for protection, but will almost certainly be a priority target for the enemy.
The Leviathan is an office block-sized vehicle with an impressive array of weaponry, Void Shield protection, and huge transport capacity. Its main armament, the Doomsday Cannon, has enormous range and will destroy most enemies in a single volley.