My apologies for dragging this from the dead, but I'm curious to know if Diabolos using Nightmare on the crawlers would work in this Assault? The idea being that hate will be removed when Diabolos is released.
The strategy, if this works, is to have the summoner move the crawlers making a path for the "feeders". The summoner would call Diabolos, do Ultimate Terror for AoE aggro, leave Diabolos out and take off (with Retreat) for a section where the guards are already fed. Once there, use Nightmare to sleep them all, then proceed to release Diabolos. Then, once the next section of guards is fed, rinse and repeat with the next batch of crawlers.
The problem with this is MP cost, but I think a BRD + RDM + Sanction/refresh + -1 Avatar perceptuation cost + mp refresh gear will help extend Diabolos's time. Unfortunatley, I don't know his mp/tick cost so I'm not sure how much it would help.

The last remaining evil white mage on Ramuh.
Killing tanks since 2004
Deep Thoughts, by Jack Handey
"I can picture in my mind a world without war,
a world without hate.
And I can picture us attacking that world,
because they'd never expect it."