6.1.2 Sentinel Mini Boss Counter
What are some of the best counters for this Sentinel before the Ultron? I know he has Bio Hazard which is going to be a pain. Only Ranked 5* Bleed Immunes I've got are Black Widow CW and IMIW at the moment, and I'm not sure if they're decent counters to this Sentinel. I can probably take my OR as well up, and will eventually for the Crossbones but I doubt if he'd be of any use against Sentinel. Any advise?