Some are great fun to open but not the best way to chase one specific card
It's a Japanese Pokmon card, that came with a Pokmon TCG Art Collection book, highlighting various bits of art from cards that have long since been released and now go for extortionate prices
Art preference aside, Erika and Venusaur are usually popular inclusions in vintage and modern sets alike, so it's clear why their combination results in such a high price
Generally speaking, in decks that are three or more colors, you want to play almost all dual lands, along with enough basic lands to support whatever ramp is in your deck (Land Tax, Kodama's Reach, Rampant Growth, et al.)
Its an example of an aggressive stax deck that is designed to compete with the strongest decks in the format
Slither Blade: a great card to buff up