When the creature side of this Adventure card comes into play, you can turn any number of tapped nontoken creatures face down, forcing them to become 2/2 Horror creatures instead of whatever they were
The draw is also very relevant for Sneaky Snacker, a staple in the deck
Both versions of Shaymin see some play in this archetype, the sky forme helpfully reducing retreat costs, and the land forme providing invaluable healing
Deadpool's card swapping ability gets miles better if you find a way to create copies of him, which is why we've seen cards like The Master Multiplied, Determined Iteration, and Orthion go up in price
However, if there are any additional costs to cast Knight-Errant of Eos, you may use convoke to pay those additional costs as well