If you Special Summon Slifer, he goes to the graveyard during that turn's End Phase
For example, Pokmon- ex type Pokmon can evolve from a non- ex Pokmon, while Pokmon- EX type Pokmon are ALWAYS Basic Pokmon cards but can in turn evolve into MEGA Pokmon- EX type Pokmon
Scarcity creates value, and if many people are going after a particular card, it eventually becomes low in supply, increasing its value over time
Like most Pokmon cards, the value of Dratini depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Delta Species)
The first two print runs of Magic now known as the Limited Edition Alpha and Limited Edition Beta sets were produced in relatively modest quantities
A tiny nick can turn a top price into a budget price in seconds