The hand size limit refers to the amount of cards a player may have in their hand at the end of their turn. The limit is six. If a player has any more than that, during that player's End Phase, they must choose cards to discard until there are only six remaining.
There are a number of cards which can influence this limit. They include:
- "Hieroglyph Lithograph": This raises the controller's hand size limit to seven, for the rest of the Duel, at the cost of 1000 Life Points.
- "Enervating Mist": This lowers the opponent's hand size limit to five, as long as it remains on the field.
- "Infinite Cards": This removes the limit on both player's hand sizes, as long as it remains on the field.