Whenever you cast an instant or sorcery spell, investigate. (Create a Clue token. It's an artifact with ", Sacrifice this token: Draw a card.")
"Every answer seems to lead to a more terrifying question."
—Jace Beleren
(08/04/2016)
If an effect refers to a Clue, it means any Clue artifact, not just a Clue artifact token. For example, you can sacrifice Wrench to pay for Alquist Proft, Master Sleuth's activated ability.
(08/04/2016)
Clue is an artifact type. Even though it appears on some cards with other permanent types, it's never a creature type, a land type, or anything but an artifact type.
(08/04/2016)
You can't sacrifice a Clue to pay multiple costs. For example, you can't sacrifice a Clue token to activate its own ability and also to activate Alquist Proft, Master Sleuth's ability.
