[Guide] Collecting Phantom Seeds

I did it a different way, worked well for me and no harm of Bigfoot.

 Spoiler

First, you start off outside the Mansion Map and enter the portal to the Left.

You'll arrive to see this:

Now, there are 2 trees in this image.
After killing them, continue left to this image:

There are also 2 trees in this image, one of which you must be ranged to hit.
After killing and looting if you found a seed, return to the portal you just came from (towards mansion) and change channels.

Once you have changed channels, heads toward the left portal and start again.

Pretty simple, and Bigfoot-free!