First, we have Geth. Geth was around by the time Mirrodin had Memnarch. If you want to read more about how he became a puppet of the Phyrexian army, go here.
So, Geth is a 5/5 Intimidating, Reanimating, Milling 6 mana Legendary Zombie. His reanimate/mill ability is just awesome, because he can create more targets for himself each time he reanimates something. And the fact that he doesn't need to tap to do that is simply amazing!
Grand Architect is a blue lord. And also an artifact lord, since he can make artifact creatures turn blue until the end of turn (maybe sticking them into a fridge?). Also, each artifact he converts to the blue side of the force pumps up his secondary ability, giving you 2 mana to play even more artifacts. Nice card, especialy in a set full of artifacts as this is.
Last but not least, the first good red planeswalker. This guy creates big elementals out of your lands, gives you tons of mana and ultimates your lands into a killing machine. Man, I SO want to build a deck that uses this guy!