This build took a big hit to its effectiveness when they nerfed the clone to use your ammo pool and paired with other additions since I first made it I've determined there's just better frames for this. If you really want to make an absolute monster of an index build that can make it past John Prodman easily, Wukong won't really get that done for you since he struggles past round 5 or so.
But this one will https://overframe.gg/build/485202/revenant-prime/revenant-prime-index-carry-overkill/

This build is OVERKILL. You do not need it to be as absurdly optimized as it is. This is meant to represent the absolute strongest version of the build I use that can be made.

This build is made to be a point carry. You can't expect to use it without picking up points and it actually very often outperforms Rhinos as a carry due to its overwhelming offensive power. The toned down version of this that I actually use (because I still need another umbral forma & don't have Primed Vigor) has no problems netting 60-90% of points scored & kill count for the team.

Swap out the 4th ability for Empower for a little extra strength before casting Celestial Twin. Assuming you use Empower before Celestial Twin, this build will give your clone a total HP pool of around 18K. So your clone is basically immortal. If they ever lose enough health to matter you just run over an energy pickup and instantly press 2 for some extra fast movement and an absolutely massive heal. Also keep in mind that your clone is invulnerable while you use Cloud Walker but they can still attack, so you can use this to safely get some extra status on an enemy if you need to. If your own shields go down you just roll for your 3 seconds of invincibility and use that time to break line of sight with any enemies. If things go wrong and you die, congratulations you're playing [Wukong], you need to die 3 more times for it to actually count.

Assuming you don't have [Primed Vigor] since it's the objectively wrong choice to pick for your big milestones until it's the only option left, you can just sub it out for [Vigor] to have a clone with just about 1k less shield and a tiny bit less Health. No big deal at all. Assuming you don't want to dump 2 umbral forma on 1 frame (can't blame you) then you are forced to use non-[Primed Vigor] and you need to forma the slot [Gladiator Resolve] is in. If you don't want this to be a 4 forma build then you just leave the exilus empty, but I assure you the extra [Enemy Radar] range is worth it so you can constantly hunt down brokers.

As for the weapons, you want to use this Kuva Nukor build https://overframe.gg/build/171954/ and make sure your clone is using it. Your clone will start shooting at enemies before you even realize they are there so you'll immediately start racking up damage and more importantly a hell of a lot of status. Your clone will also be killing enemies hilariously fast and you may even have a hard time getting to enemies before they die before round 4.

For your melee weapon you will want to be using either [Dokrahm], [Reaper Prime], or [Hate] with a heavy attack build. Tennet Livia works too but it performs best with Impact as it's innate bonus damage which is trash for anything else. The reason you need to use these 3 weapons is because of their 100% slash proc on heavy attacks as well as incredibly high damage output & crit stats. The strongest scythe for the job is the Dokrahm https://overframe.gg/build/171960/ which has the highest damage output of the 3 scythes. If you'd prefer a little more range (it makes the build feel smoother to play imo) you can use [Reaper Prime] instead which has the lowest damage of the 3 good scythes but the highest crit chance & attack speed. [Hate] has the lowest crit chance & attack speed but 30 more base damage than [Reaper Prime] and the same range. The build you use is the same no matter what Scythe (or Livia) you use.

Primary weapon? Don't even equip one. Your clone will equip the Primary over the secondary unless you specifically swap to your secondary and then to your melee weapon after using Celestial Twin to summon it. It's just extra micro management that you really don't need to deal with. Sometimes things bug out and your clone disappears for seemingly no reason thanks to DE's expert coding so don't go shooting yourself in the foot making it any more annoying to bring them back.

Arcanes? I don't use em so that's up to you. Arcane Energize is probably pretty good though.

Edit: Through playing around with the [Nukor] build I've found that if you don't want to run this build as a carry (though it does the job well I assure you) you can just remove the melee weapon and potentially use an aura forma to swap to [Corrosive Projection] or [Pistol Scavenger] (ammo is a problem in later rounds, securing kills is a smaller problem) to just melt everything from a distance. The same thing can be achieved with a good [Phantasma] build for higher damage output and the typical low density of enemies means you'll rarely miss the chaining effect. [Phantasma] has bigger ammo problems than the [Nukor] however, so for that version you may want to use Sickening Pulse over Empower to save ammo.