For all you Dark Knights out there

The whole achilles thing wasnt clear to me since a while ago I thought you would actually see the 'less' dmg you take when you get hit and when you got 1/1 you would have the % of achilles left of your MAX HP but than I heared its from the HP you got at the moment you got 1/1'd. If thats true then lets say I'd have serk30 means 10k hp to stay below than I think I should be able to use those 40% pots on 1/1. Still I dont regret getting Aura before Achilles cause it actually helps alot like some allready said.