Fellowfog, Fire-Light Phantom

Whenever another nontoken creature enters or
leaves the battlefield, investigate.
(Put a colorless Clue artifact token onto the battlefield
with "{2}, Sacrifice this artifact: Draw a card.")
Shadow of a Doubt — Pay 3 life, Discard a card:
Clues you control cost {1} less to activate this
turn. Activate this ability only once each turn.
Light the Way — Whenever you sacrifice a Clue,
draw two cards instead of one.