Crystal Skull, Isu Spyglass
Legendary Artifact
You may look at the top card of your library any time.
You may play historic lands and cast historic spells from the top of your library. (Artifacts, legendaries, and Sagas are historic.)

: Add

.
Some abilities trigger “whenever you cast a historic spell.” Such an ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered.