Sometimes Pack Rat is much slower than you need it to be, but at other times it is the only card that can win you the game
Whether they have flying printed on them, gained flying before your Archetype of Imagination entered the battlefield, try to gain it after your Archetype of Imagination entered the battlefield, or are being granted flying continuously (say, by another Archetype of Imagination), they can't have flying for any reason while you control Archetype of Imagination
This is Emeralds version of Lady Tremaine Imperious Queen, giving us a version of Genie On the Job that can take Ward characters out of play
The first number is the creatures Power and the second is its Toughness
Couple this with his Bodyguard and your opponent will find difficulty taking him out early without some form of removal or some specific cards such as Maui - Hero to All (Enchanted)
Under this paradigm, it becomes incredibly important to have a strong understanding of the relative power levels of every card in the Cube