Wow, how are you doing this? Finding such fitting and great art even for specific cards like the master. They will all get some special frame or layout treatment!
All I need now would be a cool picture of two wild elves to be perfectly happy
Well, it's pretty easy
I use deviantart a lot, specifically, this sub-category:
https://www.deviantart.com/digitalart/paintings/fantasy/popular-all-time/
There's heaps of great art on there, as long as you are good at coming up with related searches. The Drake Haven image I found easily with "drakes", likewise the Master of Pearls art I found with "pearls". Vengevine was more interesting, I ended up using "earth elemental", after "plant elemental" and "wood elemental" failed to give me art I really liked. The Flameblade Adept I found by searching for "Anubis", figuring the Egyptian god would be the most widely used humanoid jackal. Actually, I used "Anubis sword" first, but that turned out to be too narrow a search , so I widened the "net", so to say
Another site you could use is ArtStation:
https://www.artstation.com/
I don't use it a lot, but there's a lot of art on there as well, plus it's got some decent filters!