This is my [Grendel], set up to be a damage dealing buff tank.
I use a Toxin Kuva Tonkor built for Viral and Hunter Muntions, as well as an Adarza Kavat built for [Cat's Eye] and survivability.
The blank mod slot is [Gourmand] (which hasn't been added to overframe yet), the brand new [Grendel] augment for Feast, and the main reason why this build works at all.
Here is the augment description: Feast Augment: Instead of Energy, consumes 200 health on cast and 30 health drain.
So, now that we don't spend energy on eating enemies, we can reliably cast our Nourish buffs on cooldown, as well as keep Gloom up all the time.
Gloom, of course, gives us lifesteal, allowing us to keep quite a few enemies in our tummy without having to worry about the health drain, as long as we keep dealing damage. With the [Tonkor] setup I linked above, we will be able to heal fully with every shot. Also, keep in mind that you get a large chunk of heals every time you cast a Nourish buff.
So now that we have his whole kit working, let's fine tune it. With the addition of Arcane Avenger, which will proc off the health drain from [Gourmand], effectively giving us 45% flat CC with 100% uptime, and the [Adarza Kavat] [Cat's Eye] precept, we can get orange crits quite regularly with the [Tonkor].
I also use a [Kuva Nukor] built with the standard priming build, and a [Condition Overload] [Tenet Exec].