he Siege of Vraks is absolutely screaming "SUPERHEAVIES!". Also, fluffy, nasty and gory!
Also the anphlion project (IA 4) allows you to field many big nasty tyranid bugs...
Also, War for Armageddon!
I think he means a progressive campaign, where the points slowly ramps up in accordance with the players getting bigger and bigger armies - Not escalation with super heavies and gargantuans :D