Not that theres anything wrong with that, especially in Mardu, but its outclassed as a legendary tribal commander by just about every other choice in that category
Chart shows the price of Mewtwo V #72 at the end of each month going back as long as we have tracked the item.
That being said, Im almost surprised at how restrained these abilities are compared to previous Elder Dragon cycles, especially since recent creatures have trended towards higher complexity and power
I am generally a fan of Charm and Command cycles, as I think they allow for interesting gameplay, since you can change their function in the context of a given game as opposed to it being rigid in what it always does
Token producers like Ophiomancer and Jadar, Ghoulcaller of Nephalia, for example, pair extremely nicely with Sephiroth
The only things that really limit Walking Ballista are: The length of the game