Steel of the Sovereignity

Enchant creature As long as enchanted creature is white, it gets +1/+1 and has lifelink. (Damage dealt by the creature also causes its controller to gain that much life.) As long as enchanted creature is blue, it gets +1/+1 and can't be blocked.

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.) Whenever a creature you control attacks alone, you may search your library for an Aura card that could enchant that creature, put it onto the battlefield attached to that creature, then shuffle.