Igen the Dawn Titan

When Igen the Dawn Titan enters the battlefield, look at the top 6 cards of your Library. You may reveal a Historic spell with converted Mana cost of 4 or less, and place that card into your hand. Place the rest on the bottom of your library in a random order.
{3}{b}, Sacrifice a creature: Look at the top X cards of your Library where X is the Power of the sacrificed creature. You may reveal a Legendary creature or Artifact-Equipment with Converted mana cost X or less and place it onto the Battlefield