If a hardcore character dies, you cannot play with that character anymore.
Hardcore mode is the way to get more fun.
When you create a new character you can set the hardcore level. This value can not be changed later.
Hardcore characters get more experience but gets more damage from monsters by their hardcore level.
Hardcore level 1:
%500 More Experience
%0 More Monster Damage
Hardcore level 2:
%600 More Experience
%20 More Monster Damage
Hardcore level 3:
%700 More Experience
%40 More Monster Damage
Hardcore level 4:
%800 More Experience
%60 More Monster Damage
Hardcore level 5:
%900 More Experience
%80 More Monster Damage
Hardcore level 6:
%1000 More Experience
%100 More Monster Damage
Hardcore level 7:
%1100 More Experience
%120 More Monster Damage