There will be a mythic content overhaul, they're replacing the hextech thematic with new thematics and all previous prestige/mythic skins will become obtainable on an rng basis, basically. a set amount of prestige skins will be able to redeemed for a certain amount new currency replacing gemstones every few months or so and mythic skins will no longer be in the chest pools for rerolls and such. people who have prestige skins before this new system rolls out will get a special upgraded version for free.
https://www.leagueoflegends.com/en-gb/news/dev/the-mythic-content-overhaul/
"Gemstones and Prestige Points are combining into a single new currency that never expires. When the update happens, your remaining Gemstones will automatically convert to Mythic Essence at a 1-to-10 ratio, but your Prestige Points will disappear."
Basically your current gemstones get already converted to the new essence, and you can obtain the essence from future event passes.
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"Prestige skins released at least 1 year ago are eligible for unvaulting in the Mythic shop." ... "Third+ unvault: 200 ME (2018 Prestiges start here)"
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If you happen to have 20 gemstones, you will already have enough points for the skin. If you don't have 20 gemstones, your existing gemstones will be converted into 10 * gemstone
, e.x. 8 gemstones will be converted to 80 essence.
The price of the prestige will be 200 Mythic Essence.
You will have to grind for the rest of the essence with the pass missions after buying a future event pass when the changes roll out.
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link to the post for your own reading pleasure:
https://www.leagueoflegends.com/en-us/news/dev/the-mythic-content-overhaul/
Not sure if there's any other way but I downloaded the replay file and uploaded it into https://anonfiles.com/HaA1BaF3xf/EUN1-3051217293_rofl.
This was my most recent game and I realised that I go in too much.
https://www.overwolf.com/app/Amer_Yono-LeagueTracker This one, its really good, you can also change lots of things in settings etc... But you need to do it manually so its legal and riot approves it and its not a script.
Just as an update, Riot released the article for the last chance Prestige Shop. Qiyana isn't a part of that, nor was she expected to be. In the article, they mentioned that there will be a Mythic content overhaul beginning on March 15. That will likely contain the path for you to get Prestige Qiyana.
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Here's the article: Last Chance Prestige Point Shop