Powder snow is one of many new blocks added with Cliffs and Caves part 1 in Minecraft. The block itself can be used to trap either players or mobs, as it slows down movement and slowly traps both similarly to quicksand in the game.
That being said, you can collect powder snow in the game from both the new snow biomes in the game, the mountain grove, and snow slopes. However, to collect powder snow, you will need an iron bucket. You can craft a bucket with three iron ingots placed in a v pattern, as shown below.
Once made, you can then use it on powder snow to collect it by right-clicking it. Doing so will then put the powder snow inside the bucket.
When you got yourself some powder snow, you can then place it down anywhere by right-clicking with the bucket of powder snow on your Hotbar.
We recommend using the snow as a way to slow down mobs in the surrounding area of your base, thus allowing you to pick them off from range. It can also be used creatively in mob farms as well, as a way to slowly drop mobs down without killing them.