The most important factors are edition (1st Edition, Shadowless, Unlimited), condition (mint cards command premiums), rarity (holographic, secret rare, full art), age (vintage Base Set cards are highly sought after), and the Pokemon itself (Charizard, Pikachu, and fan favorites are worth more)
If a "Gear Soul - Infantry Mk.I" on your side of the is destroyed and sent to the graveyard as a result of battle, you can Special Summon this card from your hand
Blade of the Bloodchief Blade of the Bloodchief might not be as striking as some other cards, but its cheap and it likes vampires
At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.) Illustrated by Goran Josic Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Not Legal Modern Legal Brawl Not Legal Legacy Legal Comp
But what if you could access the same vault the pros use