How to clip an image/layer like photoshop to an animation that has a transparent background.

[Teodi]

Good day! I'm new to premiere pro, and here is my issue. I have an animation/sequence I'm currently compositing in premiere pro that has a transparent background and I forgot to add shadows on it, that it is supposed to look like it enters a tunnel, and I don't want to re-render my animation just for that. Is there a way to clip an image that acts like a shadow onto the animation/sequence like clipping layers in photoshop?

Assume the train is moving, but the shadow is static.

[Peru Bob]

Use an opacity mask with a black color matte under the video track.

[Teodi]

I have a background for it tho, so I can't just add a black color matte.

[Teodi]

I have watched a tutorial about using track matte, but it only works for videos clipping on an image or shape, is there an opposite way to do it?

[Peru Bob]

There is an option to invert the matte mask.

[Teodi]

can you tell me how or where it is? I only see a check box saying "reverse " but it only reverses the position of the track/sequence.

[Peru Bob]

I meant invert the mask, not matte.