How would I paint Smooth Terrain for a blood texture?

So, I already have a general concept on what I want to do. Most of the map is snow, and when someone's shot in the snow, I want the snow to go red there.

Now, this is a complicated script, so I'll specify what I want to know to make this, instead of asking for a script. -How would I check the terrain material at a player's feet? -How would I replace that terrain material with another material?

There is a property of the "Terrain" object located under Workspace which you can view/edit all the color values of all the terrain material's [select the drop down box next to the first color to see all of the colors]