You can sometimes "splash" a third, playing two colors as your base and a couple powerful cards or additional costs of another color, but I'd really focus on the two colors you want here
Sometimes your buddy you drove to the PTQ with was inconsiderate enough to Top 8 while you and your other friend met round four in the 1-2 bracket, and now youve got a few hours to kill
Make it something that can withstand the elements as well as theft
You may play it until you exile another card with Unstable Amulet
You dont have that many creature-focused decks in blue, but when you pair this blue enchantment with white or red, you can suddenly draw a bunch of cards
Creatures (30) 3 Giant Killer 4 Seasoned Hallowblade 3 Skyclave Apparition 4 Luminarch Aspirant 2 Halvar, God of Battle 3 Usher of the Fallen 2 Reidane, God of the Worthy 4 Professor of Symbology 1 Mila, Crafty Companion 4 Retriever Phoenix Planeswalkers (3) Lands (23) Spells (4) This is a classic deckbuilding study