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Ability: Deception (Same effect as Dazzling or Queenly Majesty)
Typing: Ice/Ghost
HP: 70
Attack: 80
Defense: 80 (+10)
Special Attack: 120 (+40)
Special Defense: 80 (+10)
Speed: 150 (+40)
Back in gens 4 and 5 what Froslass really stand out to me was the fact that she got the jump on every single dragon (ignoring scarf) and pretty much always killed them. Ever since fairies were introduced that small niche is obviously gone, not to mention there's more than enough dragons above 110 nowadays. The idea is to bring her up to speed, literally, by putting her above every single existing dragon in speed (fastest is Mega Sceptile at 145) and buffing the really bad SpA to something more bearable. It remains the "integrity" of the original design of the pokémon, much like Mega Glalie did for better or for worse.
The idea as far as gameplay is to be on a ridiculous speed tier and immune to priority but a way WAAAAAAAAAAAAAAAY lower special attack than Mega Alakazam to compensate. On a lore [?] kinda sense, she is a yuki-onna which tales will usually go akin to something "deceives a man and kill it", being that is literally designed around using their appearances to trick people, I feel it's somewhat justified she would know how to avoid trickery herself.
Random ass defense points because GF always does that, could be +20 in attack honestly, it won't change anything, she will still die to a breeze.