The key here is Ratchet is able to return an artifact, and because its backside is legendary, you are able to kill it using the legend rule and then return it again
The remaining three new cards arent Slivers, but are cards that play well with them or any other creature type you want to build around
BIDDER CHARGE BACKS: Bidders agree to pay all costs related to any "charge back" by banks and/or credit card companies, including fees, processing charges, collection cost, attorney and court costs
Youd be able to dust a mythic for the maximum amount of crafting currency and then make the cards that you actually want
While the MTG Strixhaven reveals of Lightning Bolt, Duress, and Time Warp are exciting just because they look so intriguing, they're also appealing because they indicate a philosophy behind the Mystical Archive's components that should make players quite happy