Gemini Summon

Second Summon is a mechanic introduced with "Tactical Evolution". Monsters that use this mechanic are treated as Effect Monsters in the Deck, but if they have not yet been Second Summoned when on the the field, or if they exist in the Graveyard, or when removed from play, they are treated as Normal Monsters. Tribute(s) for a Second Summon of Level 5 or higher monsters are not required.

A Second Summon is treated exactly as a Normal Summon, and it counts towards the 1 Normal Summon/Normal Set alloction per player per turn. Double Summon bypasses this, and allows two Normal Summons per turn, and Ultimate Offering offers an extra Normal Summon for each sum of 500 Life Points you are willing to pay.