Thought Devourer — ruling 1

If multiple effects modify your hand size, apply them in timestamp order. For example, if you are affected by Cursed Rack (an artifact that sets a player's maximum hand size to four) and then put Thought Devourer onto the battlefield, your maximum hand size would be zero. However, if those permanents entered in the opposite order, your maximum hand size would be four.

Thought Devourer : règles, fonctionnement et interactions (MTG)

Thought Devourer 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

Flying Your maximum hand size is reduced by four.

How it works : Thought Devourer

Original English text — Wizards of the Coast / Scryfall

#1October 1, 2009· Wizards of the Coast
If multiple effects modify your hand size, apply them in timestamp order. For example, if you are affected by Cursed Rack (an artifact that sets a player's maximum hand size to four) and then put Thought Devourer onto the battlefield, your maximum hand size would be zero. However, if those permanents entered in the opposite order, your maximum hand size would be four.
No other card is named in this ruling.