There are plenty of pricey chase cards you can pull (or buy individually on TCGplayer ) including SIR Mega Darkrai ex, MHR Mega Darkrai ex, SIR Morpeko ex, and SIR Mega Zeraora ex all with exceptional market prices up to just under $400
They cannot stack the +2 card with other cards
But it's also true that selling random booster packs will likely encourage spending over a longer period of time, as players hunt specific cards
One of the most dangerous cards you can play with Jumbo Cactuar is Jarad, Golgari Lich Lord
To be honest, only Deck that can even make this on a consistent basis with the standard requirements are Artifacts, but their use for this is limited at the moment to the first effect with low opportunities to use it
Theres usually not more than one serpent in a set