Its just Cats up and down, for days
Gruul is very combat-oriented, and so you can run classics like Xenagos, God of Revels, while augmenting that strategy with newer hotness like Halana and Alena, Partners and Anzrag
Tokens that leave the battlefield will satisfy a revolt ability
This is like the ongoing Collective Defiance, you get to grind down the control players by attacking their hand or gain tempo against the aggressive players by killing their dorks and absorbing attacks with loyalty rather than life
The second effect allows you to pay three mana plus one black and one red, and tap the card to deal 1 damage to each opponent, which is great in Commander Format
While those are the most notable lands, all the lands reprinted in the precons have new flavor and art to match the set, so you can trick out your mana base with FIC-flavored lands if you want