Item affix glasscannon and talent empower decrease hp but increase your damage.
Thanks for the response
Glasscannon increases Dmg by the same % that is used to lower your HP. so a +50% Dmg is -50% HP.
Empower Talent (Wizard) increases the Dmg done by your Power Stat by +2.5% per rank while lowering your HP by the same %.
both of these can be used together, but HP can only be reduce do 1, unless a monster reduces it to 0.
certain builds are impossible with only 1 HP, but if you look around the Forums, you can find many 1 HP builds that are powerful.