Plot lets you pay a card's plot cost at sorcery speed to exile it from your hand. On a later turn, you can cast the plotted card from exile without paying its mana cost, still following its normal timing restrictions.
Doc Aurlock, Grizzled Genius can make plotting cheaper, while cards that reward casting from exile naturally benefit from plotted spells. Plot essentially lets you pay for a spell now and unleash it during a more explosive future turn, a perfect fit for the glass cannon flying creature Slickshot Show-Off.
