http://mtgtop8.com/compare?l=_307943_306706_304348_304808_303223_301879_300889_299143_298705_298254_297801_296871_301504_296528_

https://www.channelfireball.com/videos/channel-mengucci-legacy-burn-2/
https://www.youtube.com/watch?v=CAzu9r8I1po

https://www.mtggoldfish.com/articles/budget-magic-99-134-tix-legacy-burn
http://legitmtg.com/priemers-primers-basics-bolts-and-burn/
https://www.mtggoldfish.com/articles/instant-deck-tech-ultra-budget-burn-legacy

Sideboard:
3-4 Vexing Shusher
3-4 Smash to Smithereens
2-4 Graveyard hate (generally favor crypt or faerie macabe VS relic)
3 Ensnaring Bridge // Ashen
3 Red Blasts
1-2 Sulfuric Vortex (1 is fine since you have 2 main)
Vexing Shusher is how you beat Miracles.
Pyroblast is your counterspell against fair decks and what allows you to force Price of Progress through counterspells. Also, being able to counter Geist of Saint Traft, True-Name Nemesis, or Show and Tell is just icing on the cake. If you’re finding a lot of Blue in your metagame, you can even go deep and throw in some Red Elemental Blast, potentially going up to a whopping EIGHT anti-Blue spells.
Show and Tell: you have two options that commonly see play: Ensnaring Bridge and Ashen Rider. Ensnaring Bridge stops Griselbrand and Emrakul, the Aeons Torn from attacking. Ashen Rider, on the other hand, shuts down Show and Tell with ease, but is a dead card against the Sneak Attack plan. However, Ashen Rider is also live in the OmniTell matchup, whereas Ensnaring Bridge is next to useless. Any Burn deck should be running at least one of these cards in their sideboard.
For creature-heavy metas, you have the option of running Searing Blood.
Your graveyard hate is limited to pretty much either artifacts like Relic of Progenitus or using Surgical Extraction. Another option is Faerie Macabre, which has the unique advantage of not being counterable (although it can still be hit with Stifle). While it doesn’t help much against Dredge.
Lastly, we have Smash to Smithereens. It is one of the best artifact destruction spells in Magic. Probably the best artifact-based counter for Burn, still get to hit the opponent for 3 damage.

http://puremtgo.com/articles/leaving-legacy-ground-floor