Policy changes for Ixalan include making sure that your opponent is choosing not to do an optional thing from one of your spells/abilities.

Ghost Quarter them? If they don't go grab a basic then you have to confirm that they are choosing not to. Ditto with Path to Exile and Veteran Explorer. :/

Link

Recently, there’s been some question about what we expect players to do when they play a spell or ability – most commonly Path to Exile, but Ghost Quarter comes up, too – and their opponent doesn’t do an optional part of the instruction. Since it’s optional, that’s theoretically a legal result, even if they didn’t realize that they had the option. Given the preponderance of textless and foreign cards, and communication rules that don’t require you to explain everything a card does (because that way lies madness), there was incentive for scurvy dogs to not bring up those parts of a card.

Revised communication rules have added text to preempt this. Now, if a spell or ability you play gives an opponent a choice, you must get confirmation from them that they aren’t doing the optional thing. You still don’t have to remind them while they decide if they want to respond, but once it resolves and the time comes, no making assumptions...