Gyra and Myra, Twin Prodigies

Whenever you cast or copy an instant or sorcery
spell, each opponent puts the top two cards of
their library into their graveyard.
At the beginning of your end step, if an opponent
has 4 or more instant or sorcery cards in their
graveyard, reveal the top two cards of your
library. You may cast an instant or sorcery card
revealed this way until the end of your next turn
without paying its mana cost.