To give your foe a basic land is indeed a downside, but a fair price to get rid of almost any threat
The fastest way to get cards in Arena is to purchase them with gems through a bundle, buy a deck in the store or straight packs and wildcards
Fans have already pointed to Strixhaven Stadium as one pre-existing card that would work extremely well with Tidus Cheer ability
Removing threats and pumping your planeswalkers is a great strategy in my book
Tarkir: Dragonstorm and Edge of Eternities also had some really powerful designs, and while they weren't my favorite Limited environments, they definitely added some great cards to Standard (honorable mention, Consult the Star Charts)
Like the mental trick with dealing with Millstone, just imagine that the exiled cards are on the bottom of your library and dont sweat it (unless your deck plans on winning with a specific combination of cards)