Hall of Mirrors is an Advanced Mage Trap Room introduced in Boss Monster: The Next Level
This card is best built as soon as possible, especially against an opponent who has gone with a Spell centric strategy.
Simply, when an opponent plays a Spell card, the player can draw a Spell card, thus giving the principle of a "reflection" theme, as proposed by the card.
The central mirror features a golden icon similar to the Boss Icon, as well as a phantom head of the same Boss Icon in the mirror.
In some myths and tales, it is believed mirrors can house spirits, and evil mirrors would house evil spirits, which is also evidenced by the two smaller mirrors off in the sides of the portrait.