Theyre even banned in Pioneer, and are the basis of the majority of land bases in Modern, Legacy, and even Vintage
While adorably retro, they never caught on
If you do, create a token that's a copy of that creature, except it's a Spirit in addition to its other types and it has "When this token leaves the battlefield, return the exiled card to its owner's graveyard." Whenever another nontoken creature you control dies, exile it
Playability is a broad category, and it is very subjective
If youve been waiting for Magic: The Gatherings return to Middle-earth with a Hobbit-focused set this year to jump into buying cardboard versions of your Tolkien favorites, weve got good news for you - and bad news for your wallet
Both are good, but Essence Flux has the benefit of making things slightly stronger