The best Kyurem cards feature this unique Dragon-type legendary Pokemon in all of its forms, switching from black to white, to its normal Ice-type version
You'll often find a way to make black mana by the time you're ready to cast your Garruk, and even if you don't, having one card stuck in your hand for a little while isn't a complete catastrophe
Compare with Chromatic Lantern from Return to Ravnica (3 drop, Lands you control have "Tap: Add one mana of any color to your mana pool." Tap: Add one mana of any color to your mana pool.) This is a solid rare
If winning is the only goal, you wouldn't
When you play it, you are able to go into your deck and find an Instant or Sorcery with a converted mana cost of two or less and put it into your hand
Maybe you can make it work in the right deck, but theres almost always a better alternative than this