I literally get to the last Kayn, then he collects his souls or whatever, and then rings start to slight under your feet which are legit impossible to dodge. How tf are you suppose to win against that?
Beatrice falls2 votesCaptain is do'able, but Onslaught Jesus Christ man (haven't tried yet, watched videos and it looks near impossible)
Takazaki1 votesdouble sona yasuo and maybe a jinx
SEKAI1 votesPlay 
, use the "fist" augment setup
I use Intimidating, Berzerker, Concussive, Goliath, Relentless. Something like that, it doesn't have to be exact. I completed Captain with 4 player-equip augs as opposed to the full 5 slots, I went in without the Relentless as I had 1 other Malphite who had it.
and build like this
(most of the time you won't finish Nashor so 
is fine)
If you use the "fist" , you can just stand and tank while you also out-damage basically anything. Most of the time you wouldn't even need to play around Kayn, just stand there and DPS while you tank like a god.
Your DPS focus would be using your W and E (and Titanic Hydra) as much as you can (needless to say, you max W first and then E, while Q is last. R>W>E>Q); this build has Intimidating (aug) which would aggro the enemy to you when you use E, this is to ensure your team's survival because you're already borderline invincible anyway so you can take some off your team.
You won't feel the invincibility until about the 2nd or 3rd instance/map, so don't get too gung-ho early on.
Your only challenge would be if Kayn pulls out his "machine gun" and starts gunning down your entire team with his big pew-pew, which you will need to advise your Yasuo to use his W. Other than that, as long as you're with a Sona, you're 99% invincible in the most straightforward meaning.
Captain can be done that way.
.........
Onslaught is a much different story tho, the difficulty spike is imho quite BS when you reach Onslaught. I have not completed it so I can't advise you on it.
my FOOD1 votesYou are a god. I tried this build and I actually passed Captain. TYSM
Vlada Cut1 votesPlay
and build like this
If you use the "fist"
Your DPS focus would be using your W and E (and Titanic Hydra) as much as you can (needless to say, you max W first and then E, while Q is last. R>W>E>Q); this build has Intimidating (aug) which would aggro the enemy to you when you use E, this is to ensure your team's survival because you're already borderline invincible anyway so you can take some off your team.
You won't feel the invincibility until about the 2nd or 3rd instance/map, so don't get too gung-ho early on.
Your only challenge would be if Kayn pulls out his "machine gun" and starts gunning down your entire team with his big pew-pew, which you will need to advise your Yasuo to use his W. Other than that, as long as you're with a Sona, you're 99% invincible in the most straightforward meaning.
Captain can be done that way.
.........
Onslaught is a much different story tho, the difficulty spike is imho quite BS when you reach Onslaught. I have not completed it so I can't advise you on it.
Do you use Transmute tho? Holy it's gorgeous. And it's true, it's easy af to beat Captain with on hit Malphite, I recommend it to anyone who tries to play him in Odyssey because of how viable it is.
Vlada Cut1 votesCaptain is easy, Onslaught is difficult. And only Rhaast shoots Ora like that, Yasuo's E can dodge it, malphite ult can dodge it, {{summoner:52}} can dodge it. The key is to have 2 or 3 teammatea running away from it so Rhaast can focus them only so others can attack him freely.
Saezio1 votesIdk Doing onslaught with 3 augments with 5 yasuo was piss easy. No voice nothing just a normal pug. But you need the correct augments. For the 2 augment mission I have to agree it is very hard with a random group but that is how it's supposed to be.
Saezio1 votesAnd captain is laughable really xD
Sirsir1 votesCaptain is fairly easy. If you have enough lifesteal on yas/Jinx and don't get too unlucky you can pound on Rhaasts ora phase from start to finish, getting huge damage. Its not that hard to dodge that attack tbh. And you can windwall Kayns version of the Ora attack.
His ring spinny attack either starts close and can be walked away from, or starts away and has a dead zone close to kayn.
His dash attack is the hardest to dodge without Fs if hes targeting you with it. You can CC him to stop at least one dash.
And in captain phase you can handle the adds. In Onslaught you can't because of the time limit.
JarodDempsey1 votesTo address ops question more directly, just have a good full augment build for whichever hero you prefer and are competent with. Examples of viable aug builds:
Ive ordered each augment set by priority, the first build for each champ are ones ive personally beat it using.
: Malphite can dps quite well but his ult becomes arguably the most important cc in the game with relentless so these two builds will be built with that in mind. The first three augs in the first build are to give him a huge taunt but also do solid damage in early stages. Relentless gives his ult infinite range and carries enemies effectively concentrating them while also applying the knockup for yas's ult. Goliath i pertsonally think malph should have when doing full slot runs because it makes him larger to block projectiles for his allies and also helps him maintain some dps for the kayn fight. Aftershock is good for dps and helpful for reaching spreadout enemies but the onslaught augment can prove to be a better option for the onslaught difficult level to provide higher uptime for his much needed ult. The second build is his on hit build and due to space and number of applicable augs theres a lot of options for his onhit build. Charged and concussive are central to the build, I add goliath because it synergizes with concussive and if he builds hp. Fracture gives you a disable in your main kit if you need one while your ult is on cooldown. Landslide gives him more aoe cc and sharpened allows him to prime targets for cc from farther away, impo i wouldnt use sharpened unless you also use landslide in which case id then recommend dropping goliath to fit those in your build. Transmute is more for pure dps and relentless is that important ult mod which is extremely useful for onslaught. One item i didnt list was unstable simply because it's a risky aug but if your looking for more of a higher risk high reward dps focused build feel free to use it.
: Jinx has some of the widest options for viable builds with siignificantly diffferent playstyles, I prefer this first one which is really heavy on cc by spamming hoppers. I also use eager+antsy to maintain high uptime of her passive in addition to unlimited mobility, alternatively you could replace the last two slots with whale bones and barrage to get a bunch more aoe although you have to manage your q a lot more to make the most use of those two augs. The second build focuses her ult since its trail can do a ton of aoe damage, the last two slots are up to you but i listed eager+antsy for the good team buffs or bamboozle+hoppers for the cc. The last build is the tank build jinx, you basically just build pure tank and get free damage. I recommend plan z + bamboozle+hoppers+scorchers+slow slow as a 3+1 or plan z + bamboozle + hoppers + eager+ antsy as a 2+2. BB+hop+scorch + slow focuses her fully on cc and enemy debuffs while bb+hop+eager+antsy has moderately high cc while also providing team and self buffs.
: The first four are integral to her harder difficulty viability and allow her to have short cooldown massive aoe cc, the last slot is a flex slot but i recommend hyped to cleanse those skarner ults, flurry would be a good option but it doesnt seem to work reliably. Sona is my least fav due to lack of fun builds and ease of running out of mana.
: i barely play yas so the first two i know are super useful while the last three arent necessarily needed though ive beat captain with this build
: Ziggs is my fav and i usually do the healing build with him but the second build listed is a solid on-hit damage build that provides him adequate selfhealing through his passive. The third build is a mine based build and works really well as sustained aoe damage so long as you have space to bounce your q, it also works well for people who dont care enough to aim well. You could exchange overkill for refresher in build 3 for more sustained dps and less burst though you also lose out on the huge damage reduction and cc invulnerability that overkill provides. Alternatively you could also switch out seekers for fallout which shifts some of your mine damage into ult damage and requires better aim to maximize mine deployment in build 3.
