These do not get added to the Standard rotation, and are legal in the eternal formats or non-rotating formats like Commander
Breach the Multiverse will mill each player for 10 to load up the graveyards, then retrieve creatures and planeswalkers from each graveyard and put them right onto the battlefield
Copying Creatures Imagine how awesome it would be to have an army of Jin Sakais in play, all of them giving evasion and double strike to many of our creatures
The trick here is keeping a whole library on your head without dropping it headwear might be a good approach
This is why Robotics Prodigy is important as a way to force a bit more consistency, but without it you're banking on drawing into them
Drawing two cards for two mana is no joke, especially if the cost is pitching a land we dont need, a spell we cant cast, or a creature we may want to reanimate later