All the cards, save for the Basic Energy cards, cannot be used in tournament play
By combining cards with amass Orcs and amass Zombies, you can end up with an Orc Zombie Army
The marquee card for Tempest was supposed to be Volrath's Helm, which, at the time, was what you now know as Mindslaver
Its also perfectly good to slot into your green deck, as the abilities are all really relevant
For example, if you're running a commander that is most powerful when itself is suited up, you want to prioritize cards like Commander's PlateCommander's Plate, Mithril CoatMithril Coat, and Blackblade Reforged
These serve as a handy reminder that you activated the power-up ability