I love that its a multiplayer-centric format
Perpetually permanently modifies the characteristics of a card, which will retain its altered stats even as it moves between the graveyard, deck, and in-play zone
For cards that instruct you to roll a d20 and have results tables telling you what that means, this can cause the die result to be higher than any of the results on the table
Still, if you don't already have the rare duals, replacing them with Contaminated Aquifer and Dismal Backwater is a fine plan for the short term, although in the long term, you'll probably need to upgrade to compete at the higher ranks
Since more than two players may be playing at one table, a Monarch may leave the game before it ends, especially if there are multiple candidates to claim the right of drawing an extra card
Please check with your country's customs office to determine what these additional costs will be prior to bidding/buying