The wards are a uncommon white cycle of five auras that appeared in the Alpha through 4th Edition core sets. Each grant a creature protection from a particular color. They were originally enchant creatures.
In color wheel order by color,
The original five were removed from 4th Edition as they were considered too weak and narrow. They were replaced by Prismatic Ward, from Ice Age, which was added to 5th Edition granted semi protection from a color of your choice. Artifact Ward, released in Antiquities, and appropriately gives a creature protection from artifacts. Flickering Ward, released in Tempest, gives protection from a color of your choice. Pentarch Ward, released in Time Spiral, gives protection from a color of your choice and a card draw. Ward of Lights, released in Mirage, gives protection from a color of your choice and can be played as thought it had flash.