Arcana measures a character’s knowledge of magic and magical creatures. It can also be used to sense whether an area has magical qualities. The most commonly used ability score is Intelligence. Examples include the following activities:
| DC | Activity |
| 10 | Notice the telltale signs of a mage’s lab; pick out a spellbook among mundane tomes |
| 15 | Detect places of latent magical energy; recall an uncommon arcane method |
| 18 | Identify the purpose of an esoteric ritual circle; notice signs of planar disturbance |
| 20 | Wow an archmage with your expertise; recreate a complex ritual from memory |