With this deck you can investigate what you want and whenever you want. Investigate that food stain on your enemy's shirt. Investigate that fly in their hair. Even investigate that gum on the bottom of their shoe.
Erdwal Illuminator: This card is pretty obvious. Get another clue off of Tamiyo's Journal, Tireless Tracker,Bygone Bishop, or Ulvenwald Mysteries.
Bygone Bishop: This card gets you off to an early start with clues and triggers off of many cards in this deck.
Tireless Tracker: Can ramp into a huge creature and gives a few clues while it's on the field. If you use it with Rogue's Passage and Confront the Unknown, the game is over really quickly.
Briarbridge Patrol: Every once in a while, this card can give a clue while blocking or attacking and can get any creature on the field for free.
Thraben Inspector: Solid one drop that not only prvides a nice blocker, but a clue to help build up strategy.
Confront the Unknown: Huge pump spell, especially when Erdwal Illuminator is in play.
Clash of Wills: Basic counterspell, usually only need to use for two mana.
Angelic Purge: Easy removal that costs only one clue to sac.
Ulvenwald Mysteries: Helps get a few clues on the board and when three are sacked with Tamiyo's Journal, you get three creatures for free.
Tamiyo's Journal: This is the real MVP of the deck. Each turn it gives one clue, sometimes a few more with Erdwal Illuminator, but the real value is in the ability. For free, you can sac three clues, allowing you to search for any card in your deck. If a counterspell is needed, tap it, if you want to put a creature on for free, tap it and make sure Briarbridge Patrol is in play. Need life? Tap it with a graf mole. It also pumps Tireless Tracker up and can give you a few 1/1 creatures. This card can do anything.
