Pyromancer Ascension is a card that has seen Modern play at varying levels throughout the history of Modern, but has never really been worth anything. It’s possible that we see that change now.
Storm is the reason that Seething Song was banned in Modern, and that ban significantly impacted the deck’s power level. Most recently the deck was slower and less resilient than Amulet Bloom while also being less consistent and resilient than Splinter Twin. With those two decks out of the format, it’s possible that we’ll see Storm rise as the go-to combo deck for the Modern format.
Storm is at pace with the aggressive linear decks of the format without the inherent weakness to Lightning Bolt. There is definitely powerful hate against the deck, though the deck looks to line up against the format well in game ones for now. Jund is basically a hate machine against Storm with discard and Abrupt Decay, but with Twin out of the format Abrupt Decay is on the downswing.
Any price movement for this one would depend on success this weekend, though the price has been creeping up for a couple months from sub-$4 to about $6. Not to mention that the spread is tiny. There are fewer than 100 listings currently on TCG Player, with very few foil copies listed that are in better than moderately played condition. The Storm archetype definitely has something to prove in Modern, but if the deck has a good weekend you can expect some serious price movement on this one.