@SamLocke Hi, there's a mask in the Pan/Crop or there's Bezier Mask in the Video FX, both can be either used to create a transparent mask or to mask/isolate an effect, Garbage Matte's are Premiere Pro.

When using the Bezier mask Curve, in General Options adjusting the Blend control will let you see what your drawing on, the Bezier mask is prob easier to use then Pan/Crop, it can be applied as many times as you wish & it can be swapped around in the fx tabs at the top of the Video FX window,