Understand that the chaotic damage and armor is what makes chaos so hard. Give a creature chaos damage and the game is ruined.
Horrors have 37500 to 40000 hp. Now just tome up a bit to say 20000 stats and you can effectively take down even legion with chaos attack, you will be dealing 100% damage to all, and take crits into consideration, evasion, self heal, need i say more? Some normal world creeps have more hp than chaotic creatures. Chaotic damage is basically 3.25more damage than hero or any other damage. and the creatures take about 3.25x less damage from all attacks. so if a creature with chaos attack of 100 hits you, you then take 325 damage. if you take 2x damage from phys attack (elementalist) you take 650 damage.
Ele takes 2x damage from attacks, but given armor and regen he can last pretty long.
the green colored damage is chaos damage, just that those widdgets is changed into gold for the game.