The Reality Stone can tap for red mana
Unsurprisingly, the commander is Caesar, Legion's Emperor, who lets you sacrifice a creature to gain two of three benefits when you attack with any creature
Because Ghost Ark only needs a crew, you can trigger it again and again, and with Imotekh or Trazyn in the mix youre banking tokens or mana each cycle
Ill get to the main list momentarily, but first Dishonourable Mentions Skyclave Apparition I know Skyclave Apparition is a good card and I accept that its probably better for the game that it exists
Summary These ten cards are more than just good spells or creatures
The Wizards Play Network has deck checklists for each set, which appear to be intended for use in limited events, but you could print them out and use them however you want