Battle of Wits — ruling 1

Battle of Wits has an “intervening ‘if’ clause.” This means that if you don’t have 200 or more cards in your library at the beginning of your upkeep, the ability won’t trigger. If the ability does trigger, but you have fewer than 200 cards in your library when the ability resolves, the ability will do nothing.

Battle of Wits — ruling 2

In tournaments, you must be able to shuffle your entire deck within a reasonable amount of time.

Battle of Wits : règles, fonctionnement et interactions (MTG)

Battle of Wits is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

At the beginning of your upkeep, if you have 200 or more cards in your library, you win the game.

How it works : Battle of Wits

Original English text — Wizards of the Coast / Scryfall

#1July 1, 2012· Wizards of the Coast
Battle of Wits has an “intervening ‘if’ clause.” This means that if you don’t have 200 or more cards in your library at the beginning of your upkeep, the ability won’t trigger. If the ability does trigger, but you have fewer than 200 cards in your library when the ability resolves, the ability will do nothing.
No other card is named in this ruling.
#2July 1, 2012· Wizards of the Coast
In tournaments, you must be able to shuffle your entire deck within a reasonable amount of time.
No other card is named in this ruling.