Best time is when the opponents are in the DPS phase of the Primeval when they are distracted and sometimes clustered, then hit them with a big damage AoE. Wiped everyone on the opposite side using Ticuu’s Divination with one designation shot and exploding them with the second.
just use the quicksilver grenada or a stasis grenade launcher trust me these 2 things go together and absolutely destroy the game making it a cakewalk to win
Easiest way to get the Army of One.... is to get your son who is a PVE freak to play a game for you, job done. Granted it's quite the upgrade path to get one of those ;)