The key to managing the first star is to heal as little as possible with essence and do as much as possible by merging on dead land. Some land gets healed by merges unfortunately, but that can't be helped.
Graves need to be in a set of 5 and 3 sets of 3 giving 5 corwin's tombs in total.
If you need room as your dragons harvest stuff, delete unwanted sprouting prism flowers, prism seeds and life essences by clicking and holding (so as not to release healing power) and clicking the bin.
Merging necromancer grass doesn't release healing power so is fine to do as needed.
Your route may vary due to the unpredictable nature of what gets healed on this level.
You can take your time to study your remaining items, the dragons will just harvest stuff you don't need and can delete (apart from the bones at the beginning).
- merge 5 gargoyle dragons (including 2 on dead land)
- and 5 crimson dragons (including 2 on dead land)
(try to merge the two sets of bones before your dragons harvest too many and turn then into life flower sprouts)
- open 1 unearthed skeleton
- merge 5 bones middle left
- merge 5 life flower sprouts
- harvest a few essence and try to heal a single grave if there isn't one already healed
- merge 1 healed grave with 2 on dead land if possible
- merge 5 bones middle right
- heal land under corwin's tomb shadow
- use corwin's tomb to open shadow land
- merge 5 life flowers including 2 on dead land
- heal as little as possible and do a 5 merge of graves
- bring a single essense to a pale square in the top 5 level 4 grimm trees and merge 4 (4 on dead land hopefully)
- do the same for the 5 top right level 4 grimm trees
- merge 5 level 5 grimm trees
- merge 3 level 6 grimm trees with one on dead land
- use it to open right shadow land
- merge 5 life flowers including 3 on dead land
- merge 5 blue life flowers including 1 on dead land
- harvest essence to get 4 small life orbs
- use two with the one on dead land bottom left and 2 with the one top right - DO NOT ACTIVATE THEM
- open more bones and merge life flower sprouts and life flowers to get more blue flowers
- merge 5 blue flowers including 2 on dead land bottom right
- merge 5 glowing life flowers including 2 on dead land bottom left
- make 2 more blue flowers and merge with one bottom right on dead land
- merge a glowing life flower with 2 on dead land bottom right
- try to heal a couple of level 3 grimm trees along the bottom row and merge 5 keeping as many on dead land as possible
- merge 3 graves top left (hopefully one or two still on dead land)
- merge 5 level 5 grimm trees along the left side (hopefully 4 still on dead land)
- try to heal the crimson dragon egg on the right with a single essence (placed one down and left worked for me)
- place a level 4 grimm tree in the hole and merge (hopefully 4 still on dead land)
this fulfilled star quests 1 and 2 for me, but if not, there are a couple more land pieces still to heal
if you still need land to heal: - try to heal as few of the remaining graves as possible to merge with ones hopefully still on dead land top right
- merge 5 corwin's tombs and merge the 2 lost souls graves with one on dead land
- activate the heal extender
- merge 3 twin life flowers (star quest 3)
- merge 3 gaia statues to win