They have summoning sickness, and so can only attack for a single turn, and can block (and die during combat)
I doubt itll show up in all that many Cubes, but I do want to invite Cube designers to take a look at all of the cards that make Clues, Food, Blood, Treasure, and all of the other incidental artifacts that show up in the average Cube game
The real issue is the bottleneck at five mana
If you are playing a deck built around something like delirium or dredge, you will want to mill yourself
I also quite loved to find Chronicle Sorceress in this set considering this cards instantly binds the two biggest icons of this game, Blue-Eyes White Dragon and Dark Magician
They can use this code in the Social Hub to see your binders