mtg each player discards a card Top 10 Opponent-Discard Cards in Magic: The Gathering Each player discards all the cards in their hand Discard any number" rules citing

The second ability of Conduit of Worlds will count spells you cast earlier in the turn even if Conduit of Worlds wasn't on the battlefield or under your control at that time

The only way to acquire Korean or Russian boxes en masse would be to be in South Korea or Russia yourself, or hope that your LGS stocks them or is willing to order them for you using whatever limited allocation Wizards gave them

Whenever you reveal a card with mana value less than the result this way, you may exile it

This is definitely a cause for concern for the average MTG Arena player who doesnt have the ability to spend hundreds of dollars on the game to keep an up-to-date deck in multiple formats