While it's normal that cards drop sharply in value immediately following release, this card's future is bright, as exclusive promo cards are limited in nature and often command more value as they become harder to find
What makes it so attractive is it plays right into an alternative wincon that has seen more play since the Strixhaven precon brought us Esix: Biovisionary
Smothering Tithe in particular plays very nicely with this card, letting you draw a card on each players turn in a Commander game
The Swinging Sphene move is a potential one-hit KO attack, with players flipping a coin to automatically knock out their opponent's Active Pokmon
However, I think what were seeing with Surging Sparks is another of the Pokmon TCG s occasional peaks, those moments when it grabs the zeitgeist once again and everyones jumping in for a bit of speculation
So all you have to do with Karumonix is build a fairly straightforward Phyrexian Rat deck, find a few ways to get them to slip through some combat damage, and start watching those poison counters tick up