This is the original Japanese Expansion Pack, the very first Pokemon Trading Card Game set, published by Media Factory in October 1996. It predates the English Base Set by more than two years and includes the original Charizard, Blastoise, and Venusaur holofoils
In The Lost Caverns of Ixalan , the artwork of each of the neon ink variants is unique to match the treatment applied to the card: green Cavern of Souls displays both a green cave as well as green neon ink
When compared to only other cards in the bonus sheet, Gemstone Caverns comes out ahead of the rest of them
There are around 40 copies of the original printing on TCGplayer, with less than half of that number being in near-mint condition numbers that would look reasonable for a mythic, not an old uncommon
Yes, double strike is one of the best ways to deal commander damage
Include a key contact for vendors to reach out to with questions