Beseech the Mirror combines an unrestricted tutor with the possibility of casting the selected card immediately. Its bargain ability lets you sacrifice an artifact, enchantment, or token as an additional cost. If bargained, it can cast the found spell without paying its mana cost when that spell has mana value four or less; otherwise, the found card goes to your hand.
Treasure, Food, Clue, and creature tokens provide convenient bargain material, although sacrificing one to bargain does not also activate that token's usual ability. Black decks with cards such as Bitterblossom can maintain an expendable resource while preserving more important permanents. The triple-black requirement favors a dependable black mana base even when the card you plan to find belongs to another color in your deck.
Four-mana engines such as The One Ring fit the immediate-cast range, while a combo deck may find a cheaper missing piece and deploy it during the tutor's resolution. The spell also remains useful without bargain when you simply need a specific card. That flexibility means it can support both planned lines and reactive searches for an answer.
Think through the sacrifice before casting. Losing an important enchantment just to save mana on the found spell may weaken the overall position. If you choose not to cast the exiled card, or cannot cast it through the offered permission, it goes to your hand. The best builds supply disposable bargain material naturally and have several worthwhile targets within the four-mana range.
