Underdome

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to pay Un-costs.

Ersta, Friend to All

+1: Create a 1/1 Human Wizard creature token that's all colors.
−3: Choose a card name from among Enlightened Tutor, Mystical Tutor, Booster Tutor, Imperial Recruiter, and Worldly Tutor. Create a copy of the card with the chosen name. You may cast the copy without paying its mana cost.
−8: You get an emblem with "At the beginning of your upkeep, if you control twenty or more Wizards, you win the game."
Ersta, Friend to All can be your commander.

Urza's Fun House

{T}: Add {C}.
{T}: Add {∞}. Activate only once and only if you control an Urza's Mine, an Urza's Power-Plant, and an Urza's Tower.
{7}, {T}: Head to AskUrza.com and click Urza's Fun House.