Ra, Expatriette, and Visionary vs. The Matriarch in Insula Primalis. How to win? That order of characters, as I rather think it would be easier if you put Visionary first.
I've suffered four massive defeats in a row. I've tried just focusing fire on The Matriarch. I tried using Twist The Ether and Liquid Nitrogen Rounds to reduce The Matriarch's attacks, but amongst Horrid Cacophany, Huginn, and Primordial Plant Life, couldn't keep them in play. Same thing with Flame Barrier.
I had a great start once, with two useless Darken The Skies and a mostly painless Horrid Cacophany followed by Brain Burning The Mask. It wasn't enough. The Matriarch flipped and started healing when she was only down to the 40s for hit points, but the heroes were already in the low teens.
I tried carefully dealing with each threat as it came out, but of course that just meant that I did a ton of damage to Cohorts and Carrion Fields rather than The Matriarch.
I can't imagine how you could bet Matriarch without Tachyon, Haka, and someone like Tempest, Adept, or Sentinels with some healing mojo. Maybe Fixer for Grease Gun. Without a way to neutralize the damage you take for killing birds, I just can't see how you could win.
We've only played against her twice, but we won the second time, thanks to Tempest's Hypersonic Assault and Haka's Savage Mana keeping the mask and cohorts from coming back into play.
If you're in a team of three and can get Stealth Bot out early, that really helps since it can cancel out the damage from the Carrion Fields and the Matriarch.
Easier said than done, as it's hard to maintain those ongoings given Horrid Cacophany, but on my second try I managed it, helped greatly by an early Volcanic Erruption. Even so Visionary got knocked out and Ra and Expatriette were in single digits at the end. Speed Loading with a couple Liquid Nitrogen Rounds and the Submachine Gun were really useful, too.