Part of the reason these cards will have risen is they're inherently awesome full art cards from a Pokmon TCG set that is getting pretty long in the tooth, and therefore harder to find
Like most Pokmon cards, the value of Nidoking 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 (Base Set 2)
Snow Mercy The holiday card of 2010 is the best ever, its flavor blowing the rest out of the water
Personally, I was trying to make the inner background of the text, black
The effect can be activated at the end of the Battle Phase, causing the opponent to remove the same number of cards on the opponent's field as the number of cards on the field