We get 300 coins as a starting bonus and can collect 800 coins every 8 hours. Adding up to a total of 9.900 coins (without freebies). Collecting times are explained at the bottom.
Dragons: Oni #254, Master #124, New: Copper #868, Darkjester #866 and at the top in the middle Skeleton King # 867.
Here are some advice for the tower:
Using the spin will cost more coins the higher you climb the tower.
You have to collect pieces for the dragons you want.
When you walk... you will only get things (gold, food, dragon pieces etc) when you land on that field with the last step. So if you have three steps you will get the thing that is on the field of your third step.
You can not walk the full amount you spinned when you hit a wall or a catapult..
Chests on the map give random resource.
Check catapults properly. Some will bring you up and some will bring you down. Sometimes two floors.
You can also buy out the last piece of each dragon. Sometimes it is better to buy the last piece instead of walking back down because you missed a piece on the way up.
On mobile devices you can check what spins will give before you walk. They are fixed. Load the game and go on flight mode. Walk with your coins and write down the results. Then close the game. Make sure it is not running in the background. Then connect with wifi (remove flight mode) and load again. Your progress was not saved. Your coins will be back again. That`s how to find the best way to use the coins.
Guide for the tower: https://dragoncityguide(dot)net/tower-island/ruined/ (replace the dot and branches with a dot)
Open the eventwindow. In the upper right corner besides the event name you see the timer .
This timer started with ....days,23hours,59minutes (on phone it doesnt show minutes).
It will count down to 00d 00h 00m.
You have three timewindows of 8 hours every day to collect 800 eventpoints (coins).
Ignore the days , just check hours and minutes of the timer.
These are the timewindos to collect the coins:
So you have 8 hours to collect the full amount of points. After that time a new timewindow will start and you start collection for the next 800 points. So it is possible to get ready with collecting 800 points ten minutes before the window ends and then after 10 minutes collect again 800 points because the next timewindow started. Just bring the time the timer shows in relation to the time your clock shows and you find the times for your timezone. I hope this is helpful.!
Edit: Costs of last pieces: Oni 75 coins, Copper 300 coins, Master 850 coins, Darkjester 1750 coins.