Currently beam of balance has a pretty big window of vulnerability at the beginning and end of the cast. The vulnerability at the beginning of the cast is fine (and makes a lot of sense given how powerful the ability and extended invulnerability can be) but there's a pretty significant window where you can get hit immediately after the cast before you can act. The only way I've found to somewhat reliably not take damage after the cast is to spam dodge (which if you have multiple dodges puts them all on CD which also doesn't feel great)
I think the ability would feel much better if you could cancel the ability when you choose, so you can play around enemy attacks and not be stuck coming out of invulnerability in the middle of an active hitbox.
It just feels particularly bad for your giant heal laser to be going on cd and the moment it ends you get hit since there's no way to predict what the field is going to look like in 8 seconds.