Mystic Mine prevents your opponent from activating any monster effects, or declaring attacks, as long as they have more monsters than you
To boil it down: 1
(That means Swiftwind Panther Warrior, Alligators Dragon Knight, Jinzo - Energy Shocker, Fisherman of Legend, Graceful & Skull Dice, Sleepy Scapegoats, Foolish Graverobber, or Reversal Box!) Then, during the End Phase, Dark Time Wizard rewinds time (but just for itself!) to place a Dark Time Wizard from your Graveyard back into your hand
Other Pokmon owned by Iono in Battle Partners [SV9] include Bellibolts pre-evolution Tadbulb, Wattrels evolution Kilowattrel, and Voltorb and Electrode (neither of which Iono actually owns in the video games)
Outside of manafixing, you want those tapped lands to really earn their place