Mono Mountains dot deck is explosive, literally (figuratively). The archetype plays multiple copies of Fireblast and Lava Dart so ending a game with little to no lands left in play isn’t uncommon. Your typical play patterns will include discarding Sneaky Snacker to a Grab the Prize or Highway Robbery, Casting a Kessig Flamebreather or Guttersnipe and launching a barrage of Lava Dart and Fireblasts.
There is a Rakdos version of this deck that leans more on the Madness mechanic and has the ability to gain life against decks where you have to race but I prefer this version in order to take advantage of how good Lava Dart is right now. There’s a laundry list of X/1s you want to be able to hit and it starts with Spellstutter Sprite. Aside from almost the entire Faeries decklist you get to knock down Delver of Secrets, opposing Sneaky Snackers, powerful mana dorks like Arbor Elf and Priest of Titania, and occasionally match up well against both sides of Lunarch Veteran, which should it ever show up against you is a nightmare. Because of Guttersnipe and Fireblast the burn deck has a lot more reach than you might initially expect.
Against this deck, count the cards in their hand and do the math keeping those previous two spells in mind, you may not be so safe at ten life. Be prepared for this deck with a plan to get your life total out of the danger zone once you’ve stabilized or finish the game quickly if the Madness deck stumbles setting up. If you wanna go fast sleeve this up, otherwise pack some Blue Blasts, Weather the Storms, or some other cheap interaction to keep pace.