Xantcha the Assassin (EDH / Commander)

Make infinite mana to drain your opponents with Xantcha.
Infinite Mana Combos:

1: Mana Geyser +Reiterate
Infinite mana if your opponents control enough tapped lands. 12 mana required to go infinite.

2:Priest of Urabrask / Priest of Gix + Nim Deathmantle + Ashnod's Altar

• Cast Priest of Urabrask or Priest of Gix
• Sac priest with Nim Deathmantle + Ashnod's Altar on field
• Recur Priest
• Each reptition will generate {R} or {B} for infinite mana, depending on which priest you got.

3: Grinning Ignus + Endrek Sahr, Master Breeder + Thermopod

• Have Endrek + Thermopod on the board
• Summon Grinning ignus, get three Thrulls
• Sac three thrulls to thermopod for {R}{R}{R}
• Pay {R} to return Grinning Ignus; gain {2}{R} for {2}{R}{R}{R} in total
• recast grinning Ignus for {2}{R}; {R}{R} left in pool; get three Thrulls, Repeat

4: Grinning Ignus + Urza's Incubator or Semblance Anvil + Prismite or Stonework Packbeast + Heartstone

• All permanents on the battlefield, Urza's Incubator Semblance Anvil with "Elemental"
• Pay red mana to return Grinning Ignus to your hand, adding {2}{R}{R}
  -Cast Grinning Ignus for {R}
  -Activate Prismite for {1} to add {R} leaving you where you started with with an additional {1}
  Repeat for infinite mana

5: Priest of Gix + Priest of Urabrask + Ashnod's Altar + Garna, the Bloodflame

• Play Priest of Gix, paying {2}{B} and gaining {B}{B}{B}
• Sacrifice Priest of Gix to Ashnod’s Altar, gaining {2}
• Play Priest of Urabrask, paying {2}{R} mana and gaining {R}{R}{R}
• Sacrifice Priest of Urabrask to Ashnod’s Altar, gaining {2}
• Play Garna the Bloodflame for {3}{B}{R}, putting her trigger on the stack and holding priority
• Sacrifice Garna to Ashnod’s Altar, gaining {2} mana
• Garna's trigger resolves, putting all 3 creatures back into your hand
• Repeat

6: Worldgorger Dragon + Dance of the Dead or Necromancy

• Have Worldgorger Dragon and any other creature in the graveyard
• Cast Dance of the Dread or Necromancy targeting Worldgorger Dragon
• Float all your mana in response (or beforehand; as needed)
• Dragon enters field; everything including Dance or Necromany gets exiled resulting in the dragon going back to the grave, which, in turn means that everything of yours re-enters the field. Respond to the Dance or Necromancy target with floating your mana again (lands re-enter untapped). Repeat at infinitum. To end the loop you have to target a different creature in your grave.