Found a stupid support build.

[zmanbuilder]

Engineer and invoker. get the broken heart relic, the emergency switch amulet, and the conservation seal ring.

You will have infinite relic uses with innate 50% use speed, so speedy use, your turret and invoker skill will last forever, and you will be pumping out huge amounts of ammo for your team.

[Toyosatomimi no Miko]

Wow. A turret with no boosted skill damage and far more ammo than even the most ammo-hungry weapon could ever need.

You're not the first to think of this either.
Had a random running this exact same build in apoc while I was co-oping with a friend Friday night. Being an ammo fountain is not helpful when ammo boxes are cheap as they are, ammo in levels is beyond plentiful, and every boss except nightweaver drops more than enough ammo, you're better off going for actual damage. You're giving up damage and proper support for being mostly useless and sitting in one shot range from most bosses and elites. If I wasn't running a medic build focused on shield spam that random would've died at least thirty separate times across the hour they were in the session.

[Tamr]

Or you could swap broken heart for bloodless and basically become invincible.

It's not a fun build, but it can cheese pretty much any content.