First, start by looking at how much the card is selling for online
In PSA 10, Gengar #57 tops the set at about $275.
Being instant speed also makes it incredibly flexible, allowing you to hold countermagic or cast this if nothing needs to be countered
The theme decks, on the other hand, will feature Escavalier and Accelgor from Red Collection as special holos
See also: Phantasmal Flames guide, Ascended Heroes guide, Master set collecting guide Will Mega Evolutions cards hold their value long-term? MHR cards have the strongest case - PSA 10 populations under 500 copies each, extreme pull rate scarcity, and Legends: Z-A demand providing a demand floor
When you do, you get ludicrously unfair card draw