Cursed Rack — ruling 1

If multiple effects modify your hand size, apply them in timestamp order. For example, if you put Null Profusion (an enchantment that says your maximum hand size is two) onto the battlefield and then a player puts Cursed Rack onto the battlefield choosing you, your maximum hand size will be four. However, if those permanents entered in the opposite order, your maximum hand size would be two.

Cursed Rack — ruling 2

The effect of lowering the maximum hand size makes it so the player discards down to 4 cards (instead of the usual 7) during the cleanup step.

Cursed Rack — ruling 3

You choose one opposing player just as this card is entering and it only affects that one player. This choice is not changed even if this card changes controllers. It becomes useless but stays on the battlefield if the chosen player leaves the game.

Cursed Rack : règles, fonctionnement et interactions (MTG)

Cursed Rack 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

As this artifact enters, choose an opponent. The chosen player's maximum hand size is four.

How it works : Cursed Rack

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 put Null Profusion (an enchantment that says your maximum hand size is two) onto the battlefield and then a player puts Cursed Rack onto the battlefield choosing you, your maximum hand size will be four. However, if those permanents entered in the opposite order, your maximum hand size would be two.
No other card is named in this ruling.
#2October 4, 2004· Wizards of the Coast
The effect of lowering the maximum hand size makes it so the player discards down to 4 cards (instead of the usual 7) during the cleanup step.
No other card is named in this ruling.
#3October 4, 2004· Wizards of the Coast
You choose one opposing player just as this card is entering and it only affects that one player. This choice is not changed even if this card changes controllers. It becomes useless but stays on the battlefield if the chosen player leaves the game.
No other card is named in this ruling.