Trace Magic Aura
Until the spell ends, you sense the lingering aura of spells that were cast within the recent past. For you to detect a spell’s aura, it must have been cast within the radius of this spell and in a location you can see. You can pinpoint the location where the spellcaster stood at the time that they cast the spell, the spell’s schools of magic, and its area of effect (if it is within this spell’s radius). If the spell is one that you know, you can identify it as such.
A spell’s magic aura can be traced for one hour per level of the spell slot used to cast it. For instance, fireball cast with a 4th-level slot can be detected with trace magic aura for 4 hours after it is cast.
Arcanist’s magic aura can erase a spell’s lingering aura or manufacture a false one. Furthermore, trace magic aura doesn’t detect castings of arcanist’s magic aura or nondetection .
Cast at Higher Levels. When using a 3rd-level or higher spell slot, you can detect castings of arcanist’s magic aura or nondetection as long as you cast this spell with a higher-level spell slot than was used to cast arcanist’s magic aura or nondetection .
Rare: Witlock’s Incriminating Trace Magic Aura. When you detect a spell’s aura, you also detect the unique magical signature of its caster. This magical signature doesn’t directly identify the caster, but any spell cast by the same spellcaster has the same magical signature. This signature can be erased but not forged with arcanist’s magic aura .