For Wandering Archaic's triggered ability, the opponent chooses whether to pay {2} before their spell resolves. If they don't pay {2}, your copy will resolve before the original spell.

Explore the Vastlands has received an update to its Oracle text. Specifically, revealing either a land card or an instant or sorcery card is optional. Any player who can't reveal a card or chooses not to simply puts all cards they looked at on the bottom of their library in a random order. Each player gains 3 life whether they revealed a card or not.

While resolving Explore the Vastlands, first the active player reveals the cards they are going to put into their hand. Then each other player in turn order does the same, knowing choices made before they choose.