When an investigator passes a Lore test while resolving a Spell effect he may spend one Clue and discard that Spell after he has finished resolving it's effects. If he does, place one Eldritch token on this card.

Does that include Lore tests on Spells triggered by Reckoning?

You mean like a Glamour?

I don't think so, I think it's only for Spells you invoke.

Glamour spells are eligible here. The mystery doesn't say anything about how the spell effect was triggered (i.e. by player or reckoning); instead the trigger for the Mystery is that investigator passes a Lore test while resolving a Spell effect.

Yeah, that was the conclusion I belatedly came to, that anything is eligible here.

It's not even ambiguous, just a bit leftbrain compared to the other blasty spells.