What kind of companion uses have you found now that they are all semi-immortal?

Now that we're not locked into 1 or 2 companions that can't die, we can finally start using them to fill the gaps in our warframe's arsenal! Did you find any good uses like that yet?

Looks like Helios is a pretty good armorstrip bot now, combining the Deconstructor with Vicious Bond.

Dethcube seems like a good fit on energy starved warframes thanks to its energy (orb) generator, possibly combined with Duplex Bond? Dunno if companion weapons ever get strong enough to kill high level enemies on their own though

I was thinking about trying out a Chesa for survival missions when you don't have a Nekros but I dunno if Retrieve helps at all since it only fires off every 10 seconds with a 45% chance of success

What kind of stuff have you tried?