If Thrumming Stone is in play, whenever you cast a spell, you can reveal the top four cards of your library and play any copies you find there for free
ETBs, promo boxes, and special edition releases appreciate fastest because: Supply constraints ETBs typically print smaller quantities than standard booster boxes, which drives up secondary market prices once retail stock depletes
There are exceptions, of coursebut in general, this is a bad trade for Gaston to make
EN boxes trade at a modest premium around $120+, though the JPN-EN gap is smaller for EB-01 than for most standard booster sets
I'd never do that to a card but the process isn't hard
The sauces, on the other hand, will be available until Aug