Enchantment — Aura, 2{W/U} (3)
Common
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 is unblockable.
Illus. Jason Chan

5/1/2008: If the enchanted creature is both of the listed colors, it will get both bonuses.
Legal in Vintage (Type 1)
Legal in Legacy (Type 1.5)
Legal in Classic (MTGO)
Legal in Commander
Legal in Modern