Once per turn, when your opponent activates a card or effect while this card is in your Monster Zone (Quick Effect), you can destroy as many cards your opponent controls as possible, then Set this card in your Spell & Trap Zone
It gets even more complicated under the old rules with damage going on the stack
It went in auction for an Eternatus-sized $900,000
Although this is the first Universes Beyond set to hit Standard, there are still plenty of powerful cards
You could get one card that sold for $50 from a $4 pack
Moreover, whenever a new Lightning-type Pokmon gets released in the years to come, well have to consider whether it could be good combined with Electric Generator Thats why I believe that, between Miraidon ex and Electric Generator, the latter is the better of the two, and why I rank it higher