Already staples in a handful of deck types since release, these Duskmourn cards deserve their high value both in game and out
Along similar lines, the card is definitely worse in sideboarded games where most decks are more likely to draw that key piece of interaction, and the more copies of Unsubstantiate you play, the harder it is to sideboard them out when you decide theyre bad against your opponents post-sideboard configuration
You also have the choice to just put it back in the command zone, which you might want to do if Grenzos not around
To play a full game, you need two sets, totaling around $32
You can find a card from The List in 1 out of 5 Play Boosters
Its worth only whatever the buyer paid for it, probably less than a dollar