Seattle 150 Rules

The 150-card Highlander format (commonly referred to as "one-fifty"), is a Magic: The Gathering format that has gained popularity in the Seattle area. Here are the rules:

A few card-specific notes:

1. According to level 4 judge Sheldon Menery, Relentless Rats only modifies the normal rules of deck construction, and so the Highlander rule takes precedence. Take it, Rats!
2. Snow-covered lands are basic lands, so feel free to add as many as you want to your deck.
3. The ante cards are, in accordance with their rules text, not legal in non-ante situations.
4. Use of proxies is up to your play group or the tournament organizer.

Mulligans: 150 uses a 3-strike "big deck" mulligan rule. If your initial hand contains 0 or 1 lands, or 0 or 1 non-lands, you can show it to your opponent, shuffle it in, and draw the same number of cards. You can do this up to three times per game. You may also take a Hyra (Paris) mulligan as many times as you like, in which you mulligan to one less card. For example, in one game you could mulligan a no-land hand, drawing 7 new cards, then if that hand is bad but does have lands, you could mulligan to 6 cards without showing your opponent. If you still had no lands, you could again reveal and mulligan to six cards again.

Discussion of the 150 format takes place on northwestmagic.com. You can find an introductory article on MtgSalvation. There's also a similar Highlander format that is apparently popular in Germany; it is documented on this site.