Well I cannot add much that what other already told you. This game is hard to play if you lock yourself into one build. I guess the fullmin could work with some armor shredding helminth?

Take an unkillable frame, like Revenant, inaros, wukong, nezha… I only started using revenant on the assassination mission for the last two runs (with xaku’s ability) and I’m surprised I never used him before for this. He will never die if you keep mesmer skin up.

Fulmin should be ok for most mobs but need to be able to kill heavily armoured mobs. I haven’t used the Fulmin in a long time, but maybe a build based on hunter munitions and slash will work. Hunter munitions drops from ghoul purge bounties in Plains of Eidolon.

Final boss will probably need something like kuva hek, or I prefer the felarx. When I started, I used mostly the zariman incarnon weapons for the assassination. Since you can’t take the fulmin, will also need a decent secondary or melee to deal with most mobs. Again, incarnon secondary weapons are really good for this. I used the laetum before, but now I use the Lex Prime with incarnon.

To be honest i wouldn’t bother about archon hunts yet. I think when it was released, we already had access to the original incarnon weapons, which made it a lot easier.

For the easiest frame option in terms of resources/time to acquire:

Step 1: Get Revenant (Prime, which should be easy to acquire)

Step 2: Get Natural Talent (the mod)

Step 3: Slap Natural Talent and ability strength into Revenant, also energy economy

Step 4: Congratz, you are now immortal with Revenant’s 2.

For the best weapons:

Felarx, Laetum, Phenmor with Devouring Attrition (the incarnon perk that gives a 50% chance on a non-crit for 2000% damage, which bypasses damage adaptation that Archons have, and will kill anything below an Archon quite easily)

For the easy weapons:

I can’t be of much help since I mainly use the Felarx, but any weapon with multishot and tons of tiny damage instances instead of one big one should do. Shotguns work well for this, provided they’re pellet shotguns and not big blasts like the Arca Plasmor.

Zariman, get Phenmor, melt Archons. You really cant get wrong with Zariman weapons from Cavalero. They are easy to get, no RNG involved, you just play missions there, get materials, and rep, and boom you have solid end-game weapons. Alternatives for Zariman weapons are Kuva/Tennet weapons, or some rare Primes, or godroll Rivens. So Zariman weapons are easiest way to get one of the best weapons in the game.

Comparing to older content Zariman doesnt have that much grind at all. You just work towards unlocking stuff and thats all, really easy and simple. Almost no RNG involved apart from getting initial bank of Entrati Lantenrs, but eventually you will have them enough, just by doing missions.

Laetus - melts everything Phenmor/Felarx - melts everything, and best Archon hunter Praedos - my to go Acolyte farmer in SP with super easy and cheap heavy attack build

And best parts about Leatum and Phenmor - they are early in reputation, so like few days worth of reputation from 0 and you have both. Laetum is actually 0 rep requirements, Phenmor is 1st or 2nd rep level

Or you can always equip Hirudo on Inaros and cheese them that way. Inaros with Hirudo is “press one button and win pretty much every content while watching Netflix”, except Arbitration, because pure melee not that good vs Arbitration drones xD You need some ranged weapon to kill Arbitration drones effectively

You need a fair amount of skill and gear to solo archon missions. They’re pretty hard. Don’t be afraid to ask for help.

Somethings you may want to grind for the gear to do them more easily:

-Arbitrations: (clear every node on regular star chart to unlock) A lot of good mods for higher level builds such as Galvanized weapon mods, Rolling Guard and Adaptation. Some mods from the mission, some come from the Arbitors of Hexis shop (does not require arbitor rep).

-Zariman: (Angels of Zariman quest) Grind up the faction rep and buy good weapons(Laetum, Phenmor) and good arcanes.

-Duviri stuff: Some of the Incarnon weapon variants are very good from SP Circuit. Reg Circuit can get you new frames and augment mods. Also other loot like new arcanes come from circuit filler loot or can be bought from the resource shop if you do the free roam missions.

-Lich/Sisters: Kuva Hek is a popular choice, but the 1 hit kill build is fiddly and takes some power house mods you might not have without doing other stuff first. Radiation is generally the best choice for Archons so check the progenitor list to correctly spawn a lich with the desired element base.

https://warframe.fandom.com/wiki/Lich_System/Progenitor

There’s a lot of good weapons for various things from Liches/Sisters.

-Helminth Uprades: (Deimos) Get the upgrade segments for your Helminth so you can mulch warframes. Every frame as 1 power that can be learned by mulching which can then be used on other frames. Xata’s Whisper (Xaku) and Roar (Rhino) are big DPS boosting powers and really useful for Archon hunting.