Just how good could it really be
The Best Cards With Split Second Spells with split second tend to cost a little more mana than their more interactive equivalents, so the best ones are either mechanically unique spells or effects that you need to resolve without your opponents' interference
So yeah, this is a situation where the circumstances of the small sets made them more exciting than the other sets, especially since the mechanics had become familiar at that point
Youll want to pack plenty of lifegain with cards such as Serras Ascendant, Authority of the Consuls, and Ajanis Pridemate to keep Heliods ability going
While the spike in price is also due to scalping (the practice of buying large quantities of popular or limited-edition products at retail price to reduce supply and increase demand), or the number of new people who only want to collect, if the card gets banned as a result of the skewed metagame, that value will likely drop, pissing off more than one dedicated collector