How do basic lands work in draft? I know you're given them, but once you choose your ratio are you stuck with it, or can you change it?

Anytime you could sideboard you can change basic lands as you please. You effectively have access to any amount of basic land, of any types you'd like, in your sideboard at all times.

In an event with decklist registration, you're required to return your deck to its original registered configuration before game 1 of each match. You'd be free to fiddle with your ratio before games 2 and 3 of each match but game 1 you're always playing exactly what you registered.

In an event without decklist registration, you're free to sideboard and tweak as you please, with no requirement to return to initial composition at the start of a match.

I believe in the events where you don't register decklists for draft/sealed you are not allowed to sideboard between match postings and the first match of the round. To avoid situations where you scouted the other decks and pre-sideboard for the opponents deck. At least that is how we always played it.

From the Magic: The Gathering Tournament Rules:


An event is usually assigned a Competitive REL if there is substantial prize involved, cash or otherwise.

No, you can change your deck at any time you like between matches--you could even sit down in front of your opponent for the next round and change your deck right in front of them, explaining to them point-blank how the changes you're making will improve your matchup. It's major angle-shooting, and if you do it you're probably taking things way too seriously and the people around you are going to think you're a jerk, but it's legal.

I did that once and then felt super bad about it.
Although I believe I lost, and to be fair, Dormant Sliver is not the best hate card (when you run it out carelessly).

Then I guess we just played it differently.

I would love someone to do this to me, I'd start laughing and peobbaly make them laugh too and feel bad about it.