how about splitting the shield time further ? .. hope it wont complicate things..
01-10% damage - 2 hr shield
10-20% damage - 4 hrs shield
20-30% damage - 6 hrs shield
30-60% damage - 12 hrs shield
60-90% damage - 14 hrs shield
90-100% damage - 16 hrs shield
Basically, the first one will automatically reset PBT when you get attacked because you will get shield every time you loose even 1%
Isn't this a better idea ?
