If this were all Solemnity did in Standard, its strength in sideboards would mostly depend on how good Temur Energy is in the format, but thankfully it does a lot more
However, a high grade doesn't automatically equal a high price
A great deck is to pair Mega Pinsir EX with six Baby Pokmon, such as 2x Mantyke, 2x Pichu, 1x Smoochum, and 1x Tyrogue (hello, Oricorio)
It was pretty obvious that a precon called Counter Intelligence was going to feature counters pretty heavily, and the box clearly showed that proliferate and artifacts were another theme but yesterday's twist was that Counter Intelligence would heavily feature a specific type of existing counter: Charge counters
In a deck like Necropotence or Death's Shadow this could be used more effectively as removal with so much control over life totals but they are not typically white archetypes