Tournament rule 602.3.d

Limited decks can use battlefields from their provided card pool or any number of "blank" battlefields. Players may opt to use “blank” battlefields in place of battlefields they received in their provided card pool.

• 602.3.d.1 “Blank” battlefields function as battlefields that do not have any rules text. Otherwise, they adhere to all other…
• 602.3.d.2 At low OPL, “Blank” battlefields can be represented by anything agreed upon by all players in the game.

Official Tournament Rules