Enchantment, 2U (3)
Uncommon
Each player can't cast more than one spell each turn.
It soon became obvious that some experiments were best overseen by fireproof teachers.
Illus. Stephen Daniele

10/4/2004: When Arcane Laboratory enters the battlefield, it will look back over the turn to see if any spell was cast before it entered the battlefield. It will notice itself being cast.
10/4/2004: If a spell is countered, it still counts as the one spell cast.
10/4/2004: When it leaves the battlefield, the effect ends and all players are able to cast spells unrestricted again.
Legal in Vintage (Type 1)
Legal in Legacy (Type 1.5)
Legal in Classic (MTGO)
Legal in Commander