Building something competitive-ish

Hi all, I’m trying to build a solid IA list and really coming up empty.

It feels like the IA units are over costed and under powered, not to mention the lack of an army rule. But still, fluff and cool just prevail, so I need to brainstorm!

I’ve got 40, primaris-sized deathwatch veterans I was thinking of as a base. They have built in re-rolls so don’t miss oath of moment as much.

But what else? Canis Rex? Sisters and immolators for 3+ save objective stuff?

What combos or units have you found work with?

I think I need to wrap my head around it not doing a lot of damage, or being resilient, and focusing on scoring.

I’d be better running as deathwatch with inquisitor allies but the restrictions are too much. I’d love to get several characters in there. A rogue trader, a navigator, an inquisitor etc. not talking top tier stuff, but trying to make things usable.