25 - Tireless Provisioner Tireless Provisioner is likely one of the best combo pieces in Magic: The Gathering, creating a Food Token whenever you play a land
A low opportunity cost mana sink that scales into the late-game is awesome, and Ill spoil the fact that the rest of the cycle did not make my list by saying that I believe Lair of the Hydra to be the best of the lot for Cube play
All commanders, to a lesser or greater degree, will push you in a particular direction, towards a particular set of strategies
Creatures that can tap for mana then untap for less than that amount of mana can generate infinite mana, and reducing those activation costs are a big part of how netting mana each iteration is possible
Though it costs a hefty seven mana to cast, since it's often played in a control deck, it is fairly easy to survive long enough to cast it
Ral Zarek is solid for your decks, and I played him in my Standard deck that did some damage at FNMs at the time, as people would really respect Ral in that era, especially with the Double Lightning Bolt available for four mana at -2