User blog comment:TheTobarMethod/HP Stacking, This Is An Issue/@comment-4888212-20130212171525/@comment-5592451-20130214004117

It does reduce the overall % damage taken if u build more health... I would like to explain more but in short:

1000 hp true dmg = 60+8% of max health = 140 = 14% of the target's health

2000 hp true dmg = 60+8% of max health = 220 =11% of the target's health

3000 hp true dmg = 60+8% of max health = 300 = 10% of the target's health