Number 69: Heraldry Crest - Dark Matter Demolition (Quarter Century Secret Rare) [ALIN-EN046] Quarter Century Secret Rare

5 Level 4 monsters
Cannot be destroyed by battle or card effects. Once per turn (Quick Effect): You can detach 1 material from this card, then target 1 face-up monster your opponent controls; that monster's name becomes "Unknown". Negate any "Unknown" effects activated by your opponent.