Mirrors are a DARK archetype introduced in Wrath of Divinity by Sound Pulse. With effects designed to negate effects by discarding cards from your hand instead, Mirrors usually swarm the Field to Synchro Summon many powerful monsters like Grand Mirrors Dragon.
There is a Loop for Fiend of the Mirrors, Grand Mirrors Mage, and Motor of the Mirrors which can be very weak unless Mirrors Cunfusion Chamber is face up. By synchro summoning 1 or 2 Grand Mirrors Mages while your opponent has two monsters on the field, then Using either the Mages effect, Firespawn of the Mirrors's (Traditional Only) effect to add 2 Fiends to your hand. Then Special Summon the two fiends and normal summon a Motor of the Mirrors and Synchro Summon a Level 6 Synchro using Motor and Fiend, preferably Grand Mirrors Warrior. then, use the other Fiend's effect and add 1 Fiend to your Hand, special Summon it again and use its effect to add Motor to your Hand. If you Summoned two Mages. you should Have 5 +2000 ATK monsters on the Field. If you used only 1 mage, wait next turn and summon Motor again, then repeat.