ON THIS WIKI
The Chaos Guardian is a mob added by the Draconic Evolution mod. It is a dragon, like the Ender Dragon, but much more powerful. A Chaos Guardian can be found on a Chaos Island. It has to be killed the same way as the Ender Dragon. When killed it will generate 1 Dragon Heart and drop experience orbs. Unlike the Ender Dragon it does not spawn a portal in the center of the island.
Almost the only way to kill a chaos guardian is fully enchanted draconic armour.
Items which may prove useful in the battle are: A signallum/lumium/enderium crossbow from Tinkers Construct. Heart canisters. The Last stand enchant together with a bunch of levels OR draconic armour. If you use both you might as well have wyvern armour with last stand and you will get killed. Some way to store large amounts of energy for your armor as the dragon drains a lot of energy.