Since I'm on a computer now, I would like to say that It's probably a good idea to switch Thoughtseizes for Inquisitions. Yes, I'm aware you can't grab so many different Good cards but, Burn has done well for 3 separate SCG's and burn spells are steadily becoming more popular (the current sleigh list being the most threatening in the current meta as it's almost all burn). The two life isn't much but, free shocks are how Conley lost the match (Game3).
Honest fact: Even though most people don't like the deck, Burn is well placed in the current meta (especially with the amount of unseasoned players) because people do not wish to acknowledge the deck. My honest opinion, "Everybody hates burn. It's the only match-up none of us can say for sure we're going to win."
This archetype does not have a great matchup vs decks with reach. We depend on being able to control what we can see then what we can imagine. So, the more reach a deck has, the worse we become against them. Counting on discard isn't the answer either as you're spending your time doing that instead of winning. Discard can not beat a topdeck.
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To elaborate on Garruk Relentless from my previous statement - Realize, I'm still running both Zenith and Mystic so I'm not playing the 'standard' version and my findings may not be the same as your own.
The biggest issue people have been having against U/W control (AKA Stoneblade) is that they have access to too many removal spells. Most people are having issues sticking a threat. Games usually take forever and us not having the ability to Brainstom with our planeswalkers makes our card selection infinitely worse than theirs.
Garruk accomplishes a stream of bodies in this instance (either Green and Black). That means that, if you take out the Feast and Famine, you've got an unlimited supply of bodies to block or swing with. The only creatures that can effectively block it are Germ (batterskull) and Factory (requires multiple) and those are only when Garruk hasn't flipped.
Additionally, Garruk doubles as removal. That means that you can kill any x/3 creature and possibly keep garruk for future use. Killing Bob, Snapcaster, Mystic, Magus(!)... isn't that bad when you can do it at the cost of less than a card.
Once flipped, the abilities may look worse but, think about it this way, You can:
Make a wall of creatures that they can't swing past without evasion (unless they want to lose creatures).
Create a stream of creatures that can't be blocked profitably.
Tutor (essentially for free) and creature remaining in your deck. Thus smoothing out draws for other spells you may want.
Create threats using other creatures you may or may not have been able to use previously (bird on turn 6 isn't as helpful as Turn 1).
The other reason I promote Garruk is Lili. She's amazing against us too since she's got the ability to kill our creatures. Yes, we can kill her (even by preemptively playing her) but what happens when she comes down and you're not prepared? Garruk's stream of tokens make it impossible for her to take over in the way she normally does.