Well, everyone knows what this is all about! Many other games have this kind of feature. Think about it and take part in the poll!
You should build the wheel with 100 gems (in the beginning of the game building a wheel is one of the tasks, like building the second builder)
To use the wheel you should spend 5 gems.
The following shows you what you may gain with it:
Nothing
15 Gems
100 Experience
10 Trophies (Not Available in Champions and Masters League)
12h Shield
Elixir (Various Amounts in Different TH lvls)
Gold (Various Amounts in Different TH lvls)
Dark Elixir (Various Amounts in Different TH lvls)
Healing Hero Immediately (Available when Barbarian King is Built)
Repairing Traps for Free
Filling Clan Castle with What was in it Previously (Available when Clan Castle is Repaired)
1h Boost for Barracks, Dark Barracks, Spell Factory
1h Resource Boost
Upgrade Walls without Using Builders for 10m
(TELL ME IF YOU HAVE MORE IDEAS)
When we gain something from the wheel, it will be stored for later usage. (Max=5)

