Like Zekrom ex, it allows you to deal more damage for each Prize card your opponent has claimed, but the cost is simply to discard an Energy
M Alakazam EX (Full Art) jumped over 400% since March, while M Rayquaza EX (Full Art) , M Gengar EX , and both M Charizard EX - 12/83 and M Charizard EX (Full Art) - 101/108 are climbing as collectors prepared for a full-blown Mega revival
Still, plenty of white decks run Farewell despite it being bad on some modes for them, and while Final Act is a bit meme-y in hitting Battles and removing counters, certain control-oriented builds in Grixis and Dimir especially would be happy to play this
Flygon's first move is called Reactive Blast and only takes 2 energy cards, 1 colorless, 1 electric and does 40+ damage depending on if you want to discard any react energy cards from Flygon while you perform the move, so in essence, Reactive Blast can do 100 damage for 2 energy cards, if both your energy cards attached to Flygon are react energy cards
Id say pretty dang strong