Cards like Demonic Tutor or Vampiric Tutor let decks find combo pieces, answers, or win conditions on demand
(You descended if a permanent card was put into your graveyard from anywhere.) Council of Echoes Four generic, two blue, Creature - Spirit Advisor - 4/4 - Uncommon Flying Descend 4 When Council of Echoes enters the battlefield, if there are four or more permanent cards in your graveyard, return up to one target nonland permanent other than Council of Echoes to its owners hand
This is, in part, because Maze's End is a solid (and extremely budget friendly) Pioneer deck and in part because among a huge number of Commander Legends : Battle for Baldur's Gate leaks, there have been some cards (including new legends) which care about the Gate land type
Lefou - Opportunistic Flunky Free is good, and in the ink color that has A Whole New World, it is even better