Avengers Assemble Vol. 4 (Avengers (1998-2004))
Collects Maximum Security: Dangerous Planet, Maximum Security #1-3, Avengers (1998) #35-44, Avengers Annual 2001.

Earth's Mightiest Heroes vs. the Universe's Mightiest Menaces! Faced with alien invaders, a gigantic killer crusader and insidious conspiracies, the heroic Avengers rebuild their operations bigger and better than ever! But are even the Avengers mighty enough to overcome a horde of Hulks, evil alchemist Diablo and an entire race of robotic menaces descended from the infamous killing machine Ultron?