Constitution is used in Dungeoneering as normal combat. Unlike in normal combat outside Daemonheim, everytime you heal yourself a purple cross "hitsplat" and the number of life points you healed will appear. It is currently not used in any kind of puzzle doors or rooms, however some puzzles would deal considerable amount of damage to those failing to solve it, thus high constitution would be essential in completing some dungeons. Some puzzles would deal over 300 point of damage at once to players, such as Lodestone room. Adding more to the basic idea of Constitution, every level up (after x10 update) you will gain 10 life points.