I posted this in another thread, but since there were so many questions on what constituted the minimum 50%:
Attacks of less than 50% maximum army capacity (based on the Army Camp, Clan Caste and Hero capacity of the defender's Town Hall level)
Here is an example from the Devs:
So let's say I'm attacking a TH10. I HAVE TO deploy at least 162 spaces worth of troops.
Max TH10 Camp Space (240)
Max TH10 CC Space (35)
Max Hero Space (50)
(FYI - if you didn't know, the game considers a hero to be 25 spaces)
So... ANY TH10 has a total # of 325.
1/2 of 325 is 162.5
At least 1/2 of a Maximum Army while attacking a TH10 is therefore 162 spaces of troops. (They rounded DOWN the 1/2)
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Also, please note, it says MAX CAPACITY FOR TH LEVEL. It doesn't matter if you are a new THx that hasn't updated their camps yet, if you have some sort of experiment base with only 1 camp, if you never unlocked heroes, etc. All villages of the same TH Lvl has the same