Wizards of the Coast's upcoming "Magic 2013 Core Set" is a fun and challenging limited format. There are a lot of bombs to open - and also a lot of duds. So cross your fingers, knock on wood, and perform every other superstitious action you can. Pray not to see these five horrible rares in your "M13" limited pool.
In the rare instance that your opponent has played Oblivion Ring on one of your threats, Worldfire can help you win a long drawn out game. Most of the time though, it'll boil down to who draws land and a cheap creature first. While Worldfire is no doubt a fun card, at ten mana and a high chance of losing I can't recommend playing with it in your limited deck.
By the time you've acquired enough mana to cast Omniscience you should be able to play every other card in your deck. Its only saving grace is that it's currently seeing a high price on the secondary market because of its potential for abuse in other formats.
Battle of Wits
Battle of Wits may be a hilarious card to base a constructed deck around, however adding some 200 lands to your limited pool isn't the smartest move. Sure, you might have a one in thirty-five chance of finding Battle of Wits in your opening hand, but do you really want to take that risk?
The "M13" limited format is a fast one, and at seven mana Hamlet Goliath is just way too slow. While Hamletback Goliath can give inevitability to your side of the battlefield, its lack of trample or enters the battlefield ability stops it from being immediately relevant. Your opponent can chump block Hamletback Goliath for several turns until they draw a Murder or finish you with their flyer.
Wit's End is worst rare in "M13." Whereas all the other horrible "M13" rares at least have their own niche uses, the usefulness of Wit's End depends on factors beyond your control. Unless you happen to be running several ramp effects the soonest you'll be able to use Wit's End is turn seven - and by then your opponent will only have one or two cards left in their hand. In comparison, Mind Rot only costs three mana.
What do all these bad "M13" rares share in common? They're either wicked expensive to cast or highly situational. While they may work when built around, these "M13" rares are horrible in limited. We hope that you open one of the most expensive "M13" rares instead.