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
Its an example of an aggressive stax deck that is designed to compete with the strongest decks in the format
Dimir is solid colors to manipulate the top of your deck, either through scrying or surveilling
Weve all seen how much popular Commanders can spike prices, after all
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.)
Soulburner is built around a reincarnation strategy, meaning that you send your monsters to the Graveyard in order to summon another copy