Unearth isnt a new mechanic by any stretch - the keyword has popped up in numerous sets since its introduction as the signature Grixis mechanic in 2008s Shards of Alara, but it makes perfect sense here
Want authentic Japanese Pokmon products
Some of them are remarkably accurate for this day and age: Since the guide came out near the end of 1999 (Fossil was released in Oct 1999), it doesnt have prices for any of the english Fossil cards: The guide also included images + translations for all Japanese cards printed up to that point, including Southern Island, and sets like Gym Heroes
Cards like Sun Titan are ideal for this plan, as you can use them to accrue significant value over time through creatures like Eternal Witness, Loyal Retainers, and Wood Elves, fetchlands like Bloodstained Mire, or even previously destroyed mana rocks, so having a big creature or two that can fill this role is very helpful when possible
As soon as protection from X is applied, if a permanent is affected, the equipment or enchantment of type X is removed