Armored Spearhead

The Imperial Guard armored company assault, supported by two Baneblade superheavies.
Despite being one of the most recognizable vehicles in the whole Imperial line-up, this 316-ton monster is rare and impractical in some cases (not helped by its rear armor being the same as the front armor of Chimera APC). Baneblades are produced on only two Forge Worlds (Mars and Lucius). However, it carries an array of various weaponry aka 11 BARRELS OF HELL: turreted Mega Battle Cannon with coaxial autocannon, a hull-mounted Demolisher cannon, three twin-linked Heavy Bolters (two sponsons and a front mini-turret) and two Lascannons (mini-turrets on top of sponsons). To leverage these things' rarity, Imperial Guard also uses lighter Macharius Heavy Tanks and in a pinch obsolete Malcador Heavy Tanks, or just lots of good old Russes.
While it is big, heavy and impractical, its chassis can carry extremely heavy weapons normally used by bigger, heavier and imractical-er Titans. Hence the Imperial Guard has a lot of self-propelled guns on its chassis, such as Shadowsword with titan-killing Volcano Cannon, Stormblade with terminator-melting Plasma Blastgun or Stormlord with horde-eating Vulcan Mega-Bolter.
Also Black Library wrote a novel about it.