The real power is likely to be the cards activated ability, which costs X to activate and reads: Exile Karns Sylex: Destroy each nonland permanent with mana value X or less
Provided you can survive a board wipe, I can definitely see this winning a game in a single swing and will massively reward the aggressive strategies that Lorcana seems to be incentivising for amber players in its third set, Into the Inklands
Following the same WotC policy, the Core Sets would come with a white border (except for Alpha and Beta, which despite being basic sets, were released in a black border)
For our non-budget list this week, we splash into black
And for cards that can trigger multiple times a turn, Annie Joins Up from OTJ is the ideal Rare Enchantment to have those triggers potentially end games
In the early game, you can create a 2/2 Knight token at instant speed with open mana