Ivory Tower — ruling 1

If you have four or fewer cards in your hand when Ivory Tower's ability resolves, the ability has no effect.

Ivory Tower : règles, fonctionnement et interactions (MTG)

Ivory Tower 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, you gain X life, where X is the number of cards in your hand minus 4.

How it works : Ivory Tower

Original English text — Wizards of the Coast / Scryfall

#1October 4, 2004· Wizards of the Coast
If you have four or fewer cards in your hand when Ivory Tower's ability resolves, the ability has no effect.
No other card is named in this ruling.