19% arcane / 20% fire elemental on bracers/neck. Everything else: see standard group builds.
Blizzard / Apocalypse for any other Fire Skill that preferably procs Chantodo stacks and Obsidian ring
Energy Armor (any useful rune) for any other useful skill depending on the situation. Good alternatives are Black Hole Spellsteal for more dps and Teleport for even more mobility outside archon.
This build is so much more fun to play and still even in theory not weaker than the standard grp build where you are stuck behind every doorway/mob/etc.
This annoys me so much that I think in 90%+ of the rifts this build here is stronger simply because you can teleport from elite to elite and won't mess up your coe/swami rotations as much as when you run with the combustion build.
Other benefits are: no more stuck trying to reach an occulust ring which of course results in even higher dps.
can only go 19% arcane (which boosts your chantodo dmg. 20% fire is needed for the chantodo wave being fire which helps igniting mobs) instead of 40% fire.
Can be tricky inside archon to ignite mobs since you need to hit an elite mob with sparkflint. But it's pretty easy to get used to.
Have fun teleporting to elites and inside occulus rings !
Hint: Never ever try going Flame Ward instead of Static Discharge. It's just never worth it. Period