I have an idea for umbrella. As the majority of those who know it can be deployed for a period of seconds and upgrades can scale it's radius and duration. It does not have any health meaning it can block as much damage as possible.
What I don't understand is it cannot block Alpha's firestorm after I did some testing myself. I believe it should be able to block such an ability which would make it a great counter to shield yourself and fellow crewmates. In exchange to balance that out is make the umbrella durable like 'Energy Wall. It can absorb much more damage and perhaps minimize the firestorm's effectiveness. For example an Alpha with it's firestorm ability at max level can destroy Umbrella by delivering half of it's total damage and then can damage robots or destroy any in critical state? I don't think it needs it's radius to scale up by level and instead umbrella can have it's duration extended by a 50% increase (max level at 22.5 seconds)