Covering a clearing on setup with your own sort of landmark is a super creative idea! And I like how you also find a way to play around with both warriors and card draw of other factions in the game at the same time. Really glad to see another faction other than my Bearcats that add in their own cards to the shared deck for folks to draw.
I really like how rotbloom is like a chain to the necropolis. A well positioned removal could trigger the removal of many, a cool way to counterplay them that's built in, I dig it!
I also really appreciate the artwork you've created, ties the whole thing together. I really couldn't see this idea being conveyed so effectively without it!
You've also definitely been paying attention when it comes to their balance, and you've given them a way to be entangled and slow others down without even the need for battling specifically. Though that option is there.
And I just now noticed they have an interactionw tih ruins too! Neat!
Great submission and I super look forward to following along as you continue this faction and with other projects as well!