I used ians guide too. R5 b1 and r4 deka (didn't need to be that high but lvl up before saw guide). Ventress 12+2 (bayonet & multitool). B2 and Maggie g12.
220 speed on deka, 6dot mods on b1: offence primaries where possible, offence and potency sets with offence secondaries.
B2 potency sets with protection.
Maggie speed set, speed arrow, protection + health everywhere else.
Ventress potency and offence sets, protection primaries.
Winning run had deka shield, they attacked Maggie who taunted on counter. Got topple and Ventress stun rex. Then took 5s and rex. Lost Maggie and b2 before topple. Took arc and echo. Gas killed Ventress but deka back to dmg immune and b1 spammed special.
Glad to never need to do this again