This is a very tricky one that gives players a tough time!

Tips
  1. Merge 5 as often as possible instead of 3.
  2. Start small -- with the Dragon Tree Leaves
  3. Work up the Dragon Tree chain until you have 2 Vermilion Dragon Trees and can heal the dead land with them using a merge with the 3rd one.

Walkthrough
Here is a full walkthrough: