Maxwell can summon famous heroes like Superman or Batman, and not only get the regular version, but most of their alternate universe counterparts, like Red Son Superman or New 52 Batman. Characters obscure like Catman or individual Green Lanterns like Kilowog or Abin Sur can be called force.
And as with Scribblenauts Unlimited, adjectives can be added - just be careful if you summon an Evil Superman.
Scribblenauts Unmasked is due to be released late 2013 on PC.