We tried Festergut about half a dozen times last week. Our first time actually knocking heads with a Plagueworks boss. I think we probably should have started with its slimier cousin, Rotface. Festergut is a gear check, with a five minute enrage timer, a huge amount of raid damage and an absurd amount of tank damage.
This isn't a strat post, since we haven't found something successful yet. Just a series of musings. In general, we kept melee and tanks in the center, on the boss, and had ranged fan out in a semi circle. Festergut will cast pools of Vile Gas at ranged targets, dealing damage and causing them to loose control and vomit, dealing yet more AoE damage to those around them and knocking them out of commission for a few seconds. Ranged should stay 10 yards apart.
However, people need to gather around players marked with Gas Spores in order to get inoculated against shadow damage to avoid a raid wipe once Festergut inhales all the Gaseous Blight and releases it again, dealing around 50k damage to everyone. So we need to gather up and make sure at least one marked player is at range and one at melee. Meanwhile, the healers can never stop going because there's large raid damage while the Blight is still out and about, and ever increasing tank damage as the Blight gets inhaled.
We never lasted longer than 60 seconds. I think I'm going to go as a tree next time. With 3 healers we almost certainly won't beat the enrage timer, but hopefully we'll live long enough to actually get some practice. Once we get used to the movement, the collapsing and spreading out, and the healing and survival cooldowns that are required, I'll try switching back to atomic death chicken mode and we'll see how it goes from there.
Of course, this all depends on the raid not falling apart after the first 90 minutes. The problems of a late night raid guild. By 2am, some people are getting a little sleepy (or, in the hunter's case, drunk).