[Noxomanus]

Well, though not shown Gandalf gives indications of what powers he really posesses with lines like "I could take It from you by force,but that would break you." or "Open your door or I blow it right through your hole" and I'm sure there are similiar other moments of indication. And who knows,on his spying mission to Dol Guldur,he might have used spells for stealth as I can hardly imagine a WizArd just walking in and out of the Dark Lord's stronghold. Perhaps he even used shape-shifting, it's indicated of the less powerful Radagast that he 'is a master of shapes and hues." It would seem likely for powerful Gandalf to posess similiar powers I think. The blowing of many-shaped and coloured smokerings might be employing a sort of spell as well.