Whenever Gollum attacks, look at the top two cards of your library, put them back in any order, then choose land or nonland. An opponent guesses whether the top card of your library is the chosen kind. Reveal that card. If they guessed right, remove Gollum from combat. Otherwise, you draw a card and Gollum can't be blocked this turn.
(16/06/2023)
If you have no cards in your library as Gollum, Scheming Guide's ability resolves, your opponent's guess will not be right no matter what they guess. That means you'll draw a card, or more accurately, attempt to draw a card from your empty library and therefore (usually) lose the game.
(16/06/2023)
You reveal the card even if your opponent guessed correctly.
(16/06/2023)
If you only have one card in your library as Gollum, Scheming Guide's ability resolves, you'll look at that card, put it back on top of your library, and then continue with the ability as normal.
