Me and 4 friends just did the odyssey 2 augment challenge without a sweat
What we did. 5 yasuos. 2 yasuos pick windwalker tempest and the other 3 wandering tempest. we build bork > ravenous > deaths dance > Phantom dance > dorans blade. (dorans blade is actually bullshit broken with 3% lifesteal)
So rng is involved tho. to get to kayn if u get a laser map. where they spawn alot of lux ulti thingies. just surrender. the rest is easy as fuk.
How to beat kayn
Blue form, when he charges his blue balls (lol) Put 1 windwall and all stand behind it. then 2nd and then 3rd. When he stands still using his slash from beneath and turning around. just kite him from behind. (both forms) when red form uses his charged up balls. 2 people kite him and attack. 3 run around the map to get some of those slashes away from the 2 attackers. When he is dashing. dont chase him until he stops or one of u knocks him up. If he spawns alot of minions, CC atleast 5-10 so the windwalker yasuos can go ham and cc most of them. When he charges up (both forms) its free damage time.
I hope any of this helps you :) 3 augment with 5 yasuos is childs play and 5 bronze can beat it. 2 augments is trickier.
EDIT: 3 of us got birdie bags. i got candy skin line (worst possible one), one got galaxy skin line (decent) and one got the entire snowday skinline .-. (best or second best skinline in terms of loot)
40% CDR Rush via BC + Caul + Kindle -> Statikk -> Infinity Edge -> Death's Dance -> Sell Kindle for a new Caulfield's. Alternatively, if you got unlucky with gold RNG spawns, Death's Dance is swapped for Spear of Shojin.
Malphite's build: 
Once again, 40% CDR Rush. Lucidity + Iceborne -> Knight's Vow -> the rest.
