Pensieve

At the beginning of your postcombat main phase,
exile an instant or sorcery card with converted mana cost less than or equal to the damage you dealt to
your opponents this turn. You may cast that card without paying its mana cost.
"I use the Pensieve. One simply siphons the excess thoughts from one's mind, pours them into the basin, and examines them at one's leisure. It becomes easier to spot patterns and links, you understand, when they are in this form."-Albus Dumbledore