When your opponent Normal or Special Summons a monster(s): Target 1 of those monsters and 1 Spellcaster-Type monster you control; send both monsters to the Graveyard, then you can Special Summon 1 DARK Spellcaster-Type monster from your Deck or Graveyard.
How to Get
Sends from your field to your Graveyard / Sends from your opponent's field to your opponent's Graveyard
Special Summons from your Deck / Special Summons from your Graveyard
I think this card is UR card. if someone set this first turn and summon a spellcaster type monster (blue dragon summoner lower ATK) and opponent set 1 card what can negate that trap, but summon a monster in ATK position... UGH.. Summon Dark Magician or better ATK monster. blue-dragon summoner is sent to the grave, add Leo. 1700+2500= 4200. if mirror wall is a set card, enemy survive for one turn. so... if someone have 3 card of this... i think next possible KingOfGames decks are Spellcaster type monsters.. or Yugi's Destiny draw skill can get easily the trap, use and when opponent summon a monster you can use it and survive. (i think if the add this card, this card is limited.)
It's a 0 (-2 because you use the trap and your monster, +2 because you send your opp monster to the grave and you special summon one).
Imagine GK: send recruiter to the grave and search, send opp monster to the grave, summon chief, bring recruiter back. Now, that's broken.