You'll ideally want an opening hand with a couple of lands and some draw/scry spells, maybe a Pyromancer Ascension
. (In reality, you'll probably get a hand of 4 lands and 3 Goblin Electromancer
s and you'll be on the Electromancer beatdown plan, but that's fun too.)
If you get a good opener, use the draw/scry spells to start digging through the deck and get a couple of counters on a Pyromancer Ascension or two. When you're ready to win, keep digging until your hand has Barren Glory, Oblivion Ring, and Worldfire, and enough rituals and Manamorphoses to generate , , and . Be sure to keep track of storm count as a decoy (definitely not for the emergency Grapeshot).
When you have everything in hand, play any rituals and Manamorphoses you need to get the required mana for the combo. At this point the storm count should be somewhere around 20, which will be a nice misdirection since it's actually irrelevant. Play Barren Glory and cast Oblivion Ring to exile Barren Glory. Then, cast Worldfire. This will exile all graveyards, all hands, and all permanents, including Oblivion Ring, bringing Barren Glory back to the battlefield. Pass the turn and cross your fingers your opponent doesn't top deck a zero-cost source of damage. If they can't, you win!
If you see a combo piece early with Serum Visions, Opt, or Sleight of Hand go ahead and drop it to the bottom of your library. You're probably going to need to cycle through your whole deck anyway, because one of the combo pieces will naturally always be on the bottom. Plus, you'll scry enough lands, extra Pyromancer Ascensions, and Goblin Electromancers to the bottom it'll push those combo pieces right back to the top.
If you mill Worldfire with Thought Scour or discard it with Desperate Ravings, don't panic! We've got Past in Flames! If you mill/discard Oblivion Ring or Barren Glory, you can scoop. I mean, you can still win with Grapeshot, but is that really a win?