Castle Upgrades
All the "Plate" improvements reduce the damage taken to bricks - with steel plates Krogons do 0 damage.
- wood plate : 3 leaf, 3 furr, 2 lighting, and 2 air.
- copper plate : 17 leafs, 21 furrs, 7 lighting, and 5 air - 12 hrs.
- steel plate : 38 leafs, 74 furrs, 25 lighting, and 13 air.
- Pond : 1 leaf, 2 furr and 2 air - 15 minutes attack delay.
- Mud : 7 leaf, 8 furrs, 2 lighting, and 3 air - 20 minutes delay.
- Sticky Swamp : 29 leafs, 45 furrs, 11 lighting, 15 air - 30 min delay- 100 hrs. to build.
- smashroom : 9 leafs, 11 furr, 5 lighting, 5 air - 1 pink smashroom per battle -5 hrs.
- flammlets : 29 leafs, 45 furr, 15 lighting, and 11 air- 20 hours.
- korgon : 53 leafs, 91 furr, 40 lighting, and 16 air - 30 hrs.
The fortifications series is handy if your castle has been damaged. Each up grade adds 50 new 
to the castle and raises the maximum hp of the castle by 50.
- Fortifications : 7 leaf, 8 furr, 2 lighting,and 3 air - adds 50 pts to walls - 12 hrs?.
- Reinforcement : 11 leaf, 17 furr, 7 lighting, and 5 air - 50 pts - 24hrs?
- Patching up : 18 leaf, 25 furr, 11 lighting, and 6 air - 50 pts - 24 hrs.
- apprentice : 3 leaf, 3 furr, 2 lighting, and 2 air - repairs 1 pt to walls every 2 hrs?.
- novice : 7 leaf, 8 furr, 2 lighting, and 3 air - repairs 1pt to walls every hour.
- Skilled builder : 17 leafs, 21 furr, 7 lighting, and 5 air. 50 hours to build
So far the best progression seems to be to build puddles then mud to give time between attacks to recover and respond then alternate with Plates and Fortifications to add points to the wall and reduce damage taken.
Sticky Swamp is expensive and takes a long time (100 hrs).