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.
Special Summons a high-leveled Spellcaster from your deck.
Can only Special Summon LIGHT or DARK Spellcasters.
Restricts your Special Summoning for the rest of the turn.
In a proper Spellbook deck, you will activate Spellbook Spells practically every turn, so Temperance of Prophecy’s effect condition would not be an issue.
Monsters to Summon
Here are some of the more powerful monsters you can summon with Temperance of Prophecy’s effect. Dark Magician of Chaos can even recover the Spellbook you used to activate Temperance of Prophecy’s effect.