Use this card together with "Marauding Captain" to be able to summon 3 Monsters in 1 turn. Simply summon "Marauding Captain" and use its effect to summon "Gemini Scorpion" and then use "Scorpion's" effect to summon 1 Gemini monster from your hand.
Use this card when you have a "Double Summon" and you can either Second Summon the Gemini monster or Tribute for "Phoenix Gearfried" on the same turn.
Special Summon this card from the Graveyard using "Call of the Haunted" or the like. That will allow you to Special Summon a Gemini Monster from your hand. If you do this at the onset of your turn or at your opponent's End Phase, you can then Second Summon your Gemini Monster and gain its effect.
If you have the means for an additional Normal Summon, select "Tuned Magician" for a level 8 Synchro monster.
Special Summon this card from the deck with "Summoner Monk" then use its effect to summon "Tuned Magician" from your hand. If you pull this off you can equip "Tuned Magician" with "Supervise" and synchro for a level 8 Monster as early as your first turn while getting a free monster from the Graveyard with the effect of "Supervise". If you have the resources to spare you can get back "Tuned Magician" and equip it with another "Supervise" to Synchro Summon another Level 8 Monster.