You launch into a recitation of obscure lore on a subject to impress, cow, or trick your audience.

Encounter
Free Action      Personal

Trigger: You would make a Bluff, a Diplomacy, or an Intimidate check

Effect: You make an Arcana check in place of the Bluff, Diplomacy, or Intimidate check.

Published in Player's Handbook 3, page(s) 165.