Lore: The Planes

Lore: Arcana represents your knowledge of the Inner Planes, the Outer Planes, the Astral Plane, the Ethereal Plane, outsiders, elementals, magic related to the planes.

Modifying ability: Intelligence

Classes: Anointed Knight, Arcane Scholar, Arcane Trickster, Archmage, Bard, Blackguard, Blood Magus, Cleric, Dissonant Chord, Dragon Warrior, Elemental Archer, Frost Mage, Harper Agent, Hellfire Warlock, Morninglord of Lathander, Pale Master, Shadow Adept, Shadowdancer, Silverstar, Sorcerer, Thaumaturge, Warlock, Warrior of Darkness, Wizard.

Requires training: No

Check: Answering a question within your field of study has a DC of 10 (for really easy questions), 15 (for basic questions), or 20 to 30 (for really tough questions).

Use: Usually none. In most cases, making a Knowledge check doesn't take an action. You simply know the answer or your don't.