Aside from all the new permanents, March of the Machine will contain some revamped cards and new instants, sorceries, and enchantments that will be great additions to any deck
Highlights include a new blue Planeswalker that can phase out your Planeswalker squad, and a flying cat monster that can double Planeswalker effects
On top of that, all damage is now dealt with wither, meaning it remains on creatures as -1/-1 counters instead of temporary damage that heals in the end step
Putting in a few battles and figuring out which cards work well and which ones aren't very useful is the best way to hone your deck
Ongoing is a supertype for schemes, and was introduced in Archenemy: Nicol Bolas
This might be a good time to consider picking up some of these if their prices drop down significantly or if you just like the new artwork