Well, GreatSeaBattle, I will tell you.
In order to be a good fit for Omniscience draft, a set has to pass two main criteria: the cards have to work the way you expect, and the cards have to be fun and different to use in a mana-safeties-off world. Throne of Eldraine failed both criteria in a variety of ways:
- Adamant costs couldn't be paid.
- Our Omniscience emblem only works on cards played from the hand, so creatures couldn't be cast from exile after going on Adventures.
- Most of the "powerful but hard to cast" budget went into strict color requirements (Adamant, the four-hybrid-mana uncommon cycle, etc), which didn't leave a ton of expensive stuff in the set to slam for free. Roving Keeps are...not exactly aspirational.
Theros and Ikoria both also had some challenges. Our emblem doesn't affect Escape costs or Mutate costs, plus both sets have mechanics that really suffer from smaller opening hands (Constellation asks you to have both a trigger and an enchantment, while Mutate needs a base creature and a mutation). That's why we never ran either as an Omniscience draft. We kept Core Set 2020 in that position for a while because it meets those requirements exceptionally well, but it was clearly starting to wear out its welcome, so we just haven't done one at all lately. (Core Set 2021 looks like it might be a good fit - maybe too good, with cards like Read the Tides and Spined Megalodon running around easy to get. It's a delicate line to tread!)
We've tried a few other draft variants; the next one is the upcoming Ikoria "Turbo Draft," where we knock 5 generic mana off all card costs. There just haven't been tons of these because we've also had Cube, Jumpstart, and now Amonkhet Remastered around to offer different kind of limited experiences. But rest assured, we are always looking for the next great pairing.