Heliod, Sun-Crowned Another newer card on the list, Heliod, Sun-Crowned is known for being both a popular EDH card (and perhaps the best mono-white commander) and a combo piece in formats like Modern and Pioneer
In the most basic format you should answer 4 questions: Who (the threat is), What (he plans to do), Where (it takes place) and Why (is he doing it)
Merfolk Skydiver is such a limited house that it's hard not to play it in Standard...it has evasion, can make something (including itself) bigger, and is an excellent mana sink in board stalls
Ghost Ark A very powerful new friend for anything from Mycosynth Golem to Platinum Emperion to Brudiclad to Sundering Titan, I love the choice to make Ghost Ark a vehicle
The Commander's Sphere taps for all of our colors and then can be sacced for a card too, but no tapping