Oracle Text

Defender, flying

T: Put Gomazoa and each creature it's blocking on top of their owners' libraries, then those players shuffle their libraries.

Card Rulings

10/1/2009 Gomazoa’s ability can be activated any time its controller has priority. It doesn’t need to be blocking any creatures.
10/1/2009 If Gomazoa isn’t blocking a creature at the time its ability resolves, only Gomazoa is put on top of its owner’s library, and only that player shuffles their library.