It's also annoying at how it triggers. I attacked a lvl 19 guy with 300k basic resources knowing that the failsave exists and tried to keep my damage low by just using 2 stacks of gold archers and pulling 1 of them back at the start with elena. Dealt 2.480 walldmg and took about 25k basic resources the first siege attack. Did the same thing again and would have gotten a bit less and the shield kicked in... like seriously it kicks in at 10% resource loss and 2.480 walldmg to a 100k hp wall.
i wonder what is the exact formula behind this
this seriously removes all the reason of defeating enemy player's defense units to plunder