Since they revealed most of the Mystical Archive bonus sheet, it's a good time for a reality check of how often all those chase mythics will show up.
7/8 packs will have an Uncommon SOA card In that 1/8th pack you have slightly less than 1/4 of a chance of a mythic and the rest are rare
Compare this to the original Strixhaven Draft Boosters:
Where Mythics were over twice as common and Rares almost 3 times as common
So the pull rates of the best cards have been heavily nerfed
Sourced from the bottom of the collecting article for SOS and the one for original Strixhaven
Ohh so these are reprints from some select list?
Yes, all regular boosters contain 1 Instant or Sorcery card from the Mystical Archive, at the above pull rates. If you check the Spoilers community you can see the current revealed cards under [SOA] (whereas the main set is [SOS])