MTG Combo: Lightning Bolt + Mana Geyser + Reiterate
All Reiterate combos require at least 7 mana to go infinite on mana when copying any spell that untaps all your stuff. Reiterate + its buyback costs 6, so the 7th mana you float to eventually reiterate another instant spell infinitely.
This combo requires the opponent to have 7 untapped lands to be able to generate infinite mana and infinite damage.