This is why we need to control biologists people! Well, this and their secret cuttlefish experimentations. Seriously though, this card is pretty awesome. It basically picks and chooses who can block it. Yeah, it doesn't have a huge body and the mana investment can get pretty expensive if your opponent has a large number of creatures, but there are other uses for it as well. For example, say you swing with a Loaming Shaman and your opponent blocks with a Faerie Macabre and gives it protection from green with his Mother of Runes. With this, one blue basically negates that protection by turning your Loaming Shaman blue. Despite the tiny body, this thing is pretty great.
Pros: Picks and chooses who can block, instant-speed colour change
Cons: Small body for cost