You can tell the rarity by the number of straight sides the icon has: the more straight sides, the rarer that card, starting from the circular common up to the pentagonal legendary rare
Nightmare Apprentice allows you to discard one card from your hand to special summon itself from your hand
destroy it, and if you do, banish 1 card your opponent controls or in their GY
Obviously you need to account for both scaling potential of the abilities and how situational they are as well
Why Pokmon Cards Are So Valuable Several factors determine the value of a Pokmon card: Rarity: Limited print runs, promos and trophy cards Condition: PSA/BGS grading, centering, edges and surface quality Popularity: Characters like Charizard, Pikachu, Umbreon, Lugia and Rayquaza Set: Base Set, Neo, EX Series, Trophy Cards, Japanese Promos and e-Reader releases History: Tournament awards, early promos and unusual distribution stories Cards from sets like Base Set, Neo Genesis, Neo Destiny, EX Deoxys, EX Dragon Frontiers, POP Series 5, Skyridge and Aquapolis continue to dominate the high-end market