I’m the rat
Ride the mammoth? Sure. I could do that at any 4th rate carny show or middle America bar on one of those mechanical mammoth rides.
But be the mammoth? Only Far Cry Primal is going to let you do that. The “Legend of the Mammoth” pack is pre-order DLC for the game, so you should probably just ignore it if it’s not important enough to make the disc. But if you’ve already got a hankering for Primal and want to mammoth up the place with three additional missions (‘Duel of Beasts,’ ‘Hunt the Hunters,’ and ‘The Trapped Elder’), make sure to pre-order soon.