Repeated instances of paying the mutate cost will get expensive (especially with the double blue requirement), but fortunately youre in a color that has some bounce capability
Realmwalker This amazing new creature is not only a Shapeshifter that can take on any other type of creatures, which is essential for any tribal deck in standard, but also a Changeling, which makes it possible to chain several copies of Realmwalker in the same turn, if they happen to be on top of your library
Magic: The Gathering as they are the primary mana source for any deck, but that sometimes leads to the physical cards being practically worthless when a new set launches
The former provides boosts to its controllers 2/2s, giving even weak vanilla and Disguised Creatures the ability to overpower opponents
At base, youre getting to boost +3/+0 twice, every time any player attacks