Kira made decks from Modern to older formats where interaction was pretty low, and she essentially gave them all hexproof
Gimli of the Glittering Caves is a mono-red double striker, and its got great legends matter and Treasure synergies
Precon Commander power level has risen so substantially that some Commanders feel at least Bracket 3 out of the box, if not with a handful and I do mean a handful of careful inexpensive upgrades
While not novel to card collecting (serial numbering first appeared on a football card in 1990), the introduction of numbered cards brought the same excitement as the previous rarity introductions in years past
Blessed Orator, Lashknife Barrier, Diversionary Tactics, and Worship combine with Squirrels to stall most opposing creature-based strategies so that you can set up something tricky later in the game (something involving Phyrexian Altar or Test of Endurance, perhaps?)
Activated ability cards have finally found a home, and its in a crazy deck utilizing Profts Eidetic Memory