Eidos & Eidolon question

First off, I love the design, probably my favourite monster in the game hands-down, appearance-wise.

The question; how do I use this charming monster (base form, not shifted) more effectively? It just seems kind of weak to me, I’ve done two runs with it so far and am struggling. Which is heartbreaking.

I ran it first on a completely uncoordinated team, but second time around I ran with Eidos, Shifted Orthrus, and base Catzerker for a sidekick-attacking team.

But Eidos was both out-dps’d and out-healed by Catzerker. The only thing it did well was preventing actions and generating aether, and there are better dedicated generator monsters.

Am I running it wrong or is it just weak?

Thanks in advance for any help!