Wand of Wonder

{4}, {t}: Roll a d20. Each opponent exiles cards from
the top of their library until they exile an instant or sorcery card, then shuffles the rest into their library.
You may cast up to X instant and/or sorcery spells
from among cards exiled this way without paying
their mana costs.

1 - 9 | X is one.
10 - 19 | X is two.
20 | X is three.