Splinter Storm's damage vulnerability doesn't affect enemies with overguard.

[greenhand0317]

Tested both in simulacrum and mission, iirc overguard doesn't block debuff like damage vulnerability.

[Tiltskillet]

 

2 hours ago, greenhand0317 said:

iirc overguard doesn't block debuff like damage vulnerability.

 

Most of them it doesn't, but it also completely blocks Qorvex Containment Walls and Equinox Rage vulnerabilities. 

I'm not saying it's not a bug, just adding some context.  I think it's even more likely to be a bug with Splinter Storm than the others, because unlike those, it's not even associated with a CC.