I struggled finding sources on how to make puddles in landscape materials when I was working on my material months ago. There are guides but for some reason google/Youtube doesn't show them or they are hidden in 5+ year old AutoLandscape Material Content. So here is the best way I found to make them.

Side Note:Adam Funari Puddle material is worth looking into for pure cinematic scenes. Use an Alpha Brush for extra control. But I'd personally use puddle decals for cinematic for the same reasons. https://axton.artstation.com/projects/nYeAJe
Adam Funari Material
Updated: New Material