原文Spells that were cast before Brimstone Roundup entered the battlefield count. If Brimstone Roundup was the first spell you cast this turn, the next spell you cast this turn is your second spell.
原文Plot abilities are written “Plot [cost],” which means “Any time you have priority during your main phase while the stack is empty, you may pay [cost] and exile this card from your hand. It becomes plotted.”
原文Exiling a card using its plot ability is a special action. Once you announce you’re taking that action, no other player can respond by trying to remove that card from your hand.
原文You can’t cast a plotted card on the same turn it became plotted. On any future turn, you may cast that card from exile without paying its mana cost during your main phase while the stack is empty.
原文If you’re casting a plotted card from exile without paying its mana cost, you can’t choose to cast it for any other alternative costs. You can, however, pay additional costs, such as kicker costs. If the plotted card has any mandatory additional costs, those must still be paid to cast the spell.