I cant name every good or useful card in each set without writing a textbook, so consider these my biased highlights
Triggering off targeted effects from your opponents is just entering silly design territory, and it earned Nadu a much-deserved spot on the Commander ban list
items and locations are joining characters for the Enchanted treatment
The battalion trigger on Boros Strike-Captain essentially impulse draws a card each turn, and even better, you can play the exiled card on any turn you've enabled battalion
The corrupting reach of the Phyrexians is now multiversal, penetrating planes both familiar and unknown
Sometimes your cards get into a fight with the crimping machine, and, well, the crimping machine wins