We're not even a MINUTE in and this is already bullshit: If you stay and listen for too long, you get forced into a cutscene that pushes you towards the later opponents without giving you the chance to play for better cards
If a monster(s) is Normal or Special Summoned to your opponent's field, while this card is in your Monster Zone (except during the Damage Step): You can Fusion Summon 1 "GMX" Fusion Monster from your Extra Deck, by shuffling its materials from your field, GY, and/or banishment into the Deck
That said, it isn't broken, but it is a great generic trap, if that counts for anything
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Gerrard, Weatherlight Hero is a great General for this strategy, as your board control options will largely not affect you when you blow up everyones creatures and artifacts, youll get yours back easily enough, and repeating this turn after turn with Oblivion Stone will soon tire resources
You may choose an artifact card from it