Devilish Valet benefits greatly from token generators, especially Myrel, Shield of Argive whenever it attacks or Geist-Honored Monk to exponentially increase the devils power when it enters the battlefield
Scourge of the Throne if a 6/6 for six mana that has flying and Dethrone, which means it gets a +1/+1 counter on it when attacking the player with the most life
Even the mechanically unique Secret Lair cards that we do get dont tend to be that strong, in the grand scheme of Magic
Starting Town, for example, improves the deck's colored mana consistency in archetypes like Jund Roots, Boros Mice, Orzhov Sacrifice, Jeskai Artifacts, Rakdos Aggro, Jund Midrange, Esper Pixie, and more
This Commander was once considered one of the scariest that a player could come across
Reyhan, Last of the Abzan) except they can only pair up with the specific card you partner with