Gnat Miser

• WWizards of the Coast2009-10-01
  Official Ruling
  If multiple effects modify a player's hand size, apply them in timestamp order. For example, if you put Cursed Rack (an artifact that sets a chosen player's maximum hand size to four) onto the battlefield choosing your opponent and then put Gnat Miser onto the battlefield, your opponent will have a maximum hand size of three. However, if those permanents entered in the opposite order, your opponent's maximum hand size would be four.

Rulings via Scryfall