We do sort of have a Rotobrush in Davinci!
With #Davinci 18 we have the depth node that allows you to actually make rotoscoping so much easier. This in combination with Magic Masks can be an ideal workflow for compositing foreground live footage over CG elements by combining a magic mask from the colour tab with a depth mask in Fusion.
You can also use it to create "realistic fog" over a scene. This is #AI #blackmagic so cool!
You bring whatever you want in "focus" with the near and "far" sliders. Gain it up with an curves or using channel operations in code (greater than) and isolate depth. Throw down some easy garbage mattes and you can quickly #rotoscope something.
I realised that shooting on RAW would really help out because you have more information for each pixel. This was shot this in ProRes.