I just recently did the tank fight on my challenge account! All the weaponry should be available to any tenno MR 10 and up.
First, some taxes.
Forma: 7
volt (2), latron (1), dualtox (1), sancti magistar (2), shade (1)
Archon shard: 5 - 15 depending on your drops
amber tauforged (2, parkour velocity), blue tauforged (1, health regen), violet/red tauforged (melee critical damage)
Orokin reactor: 2
Orokin catalyst: 3
Incarnons: latron, either lex or dual toxocyst (honestly, sidearm of your choice), magistar
Arcanes: Aegis (shieldgating), Nullifier (resist magnetic procs), Primary Crux (status chance), Secondary fortifier (overguard), Melee exposure (additional corrosive damage)
Now that we've got the investments out of the way!
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Here's the boy! His main purpose for this build was to not touch the ground for very long, hit the ground real hard when he does, and immediately get back into the air if something knocks him out of the sky.
Volt Build:
This one took the most grinding, and the perita rebellion event saved me on that aegis.
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Admittedly, my latron build is kind of ass. This account is for seeing how much I can do with just grinding below MR 10 (otherwise i would have the latron prime RIP) BUT! Anywho! The latron's in the fight for one reason and one reason only: the incarnon strips armor and that tank is made of the stuff TuT
Latron build:
Incarnons for this were Riddled Target, Extended Volley, and Flensing Spikes.
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Dual Tox Build:
Yet again, nothing too fancy. This is for giving eximus units a little lovetap and taking their overguard before you touch the ground to grab rockets.
Incarnons for this were Carnage Reign, Evolved Autoloader, and Commodore's Fortune.
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This is the bread and butter of the build, and is a setup I got from the lovely @wishvials (who hates the tank so much that she has the glyphs of all the Hex, the mad bastard). Sancti not required, but I like the fact that it swings a little faster.
Sancti Magistar Build:
Incarnons for this were Edge of Justice, Seismic Slam, and Critical Parallel.
Keeps you hidden while you tend the consoles, keeps your shields up, and he just sort of looks like a chewed bit of gum while you bounce around the arena. But any sentinel that helps you shieldgate shieldgate shieldgate will be lovely! He's just my favorite little guy.
Now let me tell you: the way I fight the tank is a bit clunky. Other people have a lot of luck with the Vazarin power Protective Sling, but I could never get that to work for some reason. But sometimes you just have to bang your head against the brick wall until it breaks TuT. I've also heard of people using the Vasca kavat because it rezzes you! I have not tried that one, but that might work for you!
Some other fun builds I have tried with the tank involved Titania's subsume to get rid of status effects, Valkyr's warcry - sometimes you just want to hit really hard and really fast, and the Coda Motovore, which is better to the Magistar in every way but radius and this is the hill I will defend.
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The method to the madness is:
You go in with your incarnons all full. (Be better than me, I forgot and had to bounce around the arena very fast and very scared until my guns screamed).
You nail the tank until the yellow health bar turns red.
Then, you heavy melee attack the tank's weak spots with your magistar (the radius makes it so you just sort of have to look in the general direction of the weak point).
Guys start falling from the sky, if you can shoot them down before they touch the ground they take a lot of damage, if you can't, then hit them with the latron and your sidearm! Rinse and repeat.
General Tips:
Stay in the air if at all possible, the ground hates you. Try not to get stuck in corners, they also hate you. There is a lovely bit of techrot wire that looks like you can stand on it at the far end of the plaza. SURPRISE! It hates Volts and likes to grab them midair and to hold them still while the tank absolutely obliterates them with horrid goo.
Anyways! You got this!