Thanks to disguises, weve already got a decent amount of support for face-down cards in the current Standard format
Back in Town offers mass reanimation at a cheaper cost than similar effects, with the caveat that you're more restricted on the types of creatures you can get back
Once Oloro hits play, things get even better, as it becomes a terrifying draw engine to boot
Its an incredibly fun-looking line-up, with everything from group slug to delirium, and some twists on old favorites
Copy effects last as long as their abilities declare, regardless of changes to the status of the card that became a copy
There are plenty of resources on this topic around, but none which both span the whole history of the TCG and employ a consistent methodology