Flickering Ward

Super handy on any white deck, I have three of them in my mono-white deck with creatures with protection, is a blessing against green decks

Simply a wonderful card, and for a few reasons. The first obviously being that it grants the protection you need, but because you can return it to your hand for the very cheap cost of one white mana. You can save it when your creature dies so you can enchant another with it, or you can just return it to your hand and jump it to a more valuable creature. One hideously broken combo is combining Flickering Ward with Celestial Ancient (from the Ravnica block.) Since you return the enchantment to your hand and replay it, the special ability of Celestial Ancient reapplies and you can give your creatures an obscene amount of +1/+1 counters. In just a few turns, your monsters become 10/10 (or more) beasts.

This is one of the most useful white enchantments in the game! With most opposing decks using some sort of targeting spells or colored creatures, you can walk on them w/ your critters.