The Astral Codex

When The Astral Codex enters and at the beginning of your upkeep, turn to a random page.
(To turn to a random page, roll 1d100 and consult the Astral Codex's Contents.)

{2}: Turn to a random page. Any player may activate this ability. Activate only as a sorcery. This ability costs {1} more to activate for each time it has been activated this turn.