Protection bonus

How is the defense bonus calculated before the attack on the Islands of different complexity ? There is an official, exact values ? 

Here is an example 1 of the skull. Ratio 1 to 1


Here is an example 2 of the skull.
Here you can see that 19K protect more than give the advantage to 56K
It turns out 1 star from above, gives +3 to the advantage

Later these same 2 skulls…
Here you can see that 10K over protection give an advantage to 50K
Is obtained 1 star above, gives +5 to advantage

The defender gets a 25% bonus on a 2 skull. No bonus on a 1 skull. 

25 % of your stars, right ?)
And the rest of the skull ?

The attacker needs to score 25% more points than the defender. 

Hi ZuZuu,

is this thread answered with what Dumpster said for you or do you need any more information?