Temperance of Prophecy (REDU-EN017) - Return of the Duelist Unlimited

During your Main Phase, if you have activated a "Spellbook" Spell Card previously this turn: You can Tribute this card; Special Summon 1 Level 5 or higher LIGHT or DARK Spellcaster-Type monster from your Deck. You cannot Special Summon another Level 5 or higher monster during the turn you activate this effect.