A Clue is a colorless artifact token with the ability ", Sacrifice this artifact: Draw a card." So, as you can see, whenever a spell or ability tells you to Investigate, what you're really doing is making a Clue that can be turned into a card later
You can follow any principles for sorting your Magic cards
Cards that cantrip (draw a card for one mana) are also a vital part of the strategy
Even if you play it on turn one, you're likely to get a couple of hits in before your opponents can get blockers up , and a few turns later you can level the class up to recover an important instant or sorcery from your graveyard
There's no restrictions on stats, type, or mana value of the creature being brought back to the battlefield, and the only thing you have to give up to play it is the three generic, one white to play it