I still have issues with mythic tokens primary use is to avoid a mythic effect. Essentially, it is McGuffin difficulty that overcoming it means using 3 anti-McGuffin tokens. So far, mythic sounds identical to everything else plus a McGuffin v anti-McGuffin mechanic. As players, we can artificially create this without spending $10K to get there just by how we decide to run or build our characters within any organized group.
I strongly recommend that Mythic be designed to be a wholly different framework than the regular game.
Please don't make Mythic effects that require specific mythic tokens to overcome. Instead, think of it like Safehold 1 means the gods have recognized you as worthy of a higher level of quest. Maybe this becomes something like a living campaign. While on the mythic quests, you advance heroic levels with new/different character cards. Because these quests are a secret of the gods, the mythic heroic levels are only usable on mythic quests (otherwise, back to regular character cards.)
In those quests, you would be facing much more powerful creatures - many times the challenge you previously faced. Higher DC's, much more damage, armor making a difference to damage, etc.. Perhaps completing X number of quests allows you to forge something new (possibly minor artifacts) and earn titles, etc.. The mythic tokens wouldn't be requirements for those adventures, just a SH1 as the requirement. You'd want the mythic tokens if the challenge level of the mythic quests was so extreme that you normally don't survive.
Operationally, this means having another set of monster stats that the DMs would run and likely changes to puzzle clues, etc. I'd recommend limiting who could DM mythic since so much of it would need to be different to be worth doing. Ideally, mythic quest runs would be set times and fairly limited (and limiting that players can only try it X number of times.) I'd also love to see something new/different that only appears in mythic runs for these. Maybe an extra NPC or alternate puzzle/monster.
Fred