The Big 4 is a group of legendary warrior of the two main warring tribes, The somewhat peaceful Overworld against the brutal and ferocious Underworld. Each of the Big 4 are close to unmatchable in strength or sometimes their special capabilities in the case of Heptadd being one of the only creatures with 4 Elements.
The name "Big 4" is similar to the Greek Mythologies, "Big 3" consisting of Zeus, Poseidon and Hades who are the most powerful and respected men/gods in their domains. In the same way, the Big 4 represents the 4 strongest creatures of their tribe.
The Big 4 Consists of
Ruler of the Overworld. With 100 Courage, Extremely High Wisdom and Energy mixed with his double Fire and Earth Element and his intensely high Mugic Counters. Maxxor is possible one of... if not, the most powerful of the Big 4
Ruler of the Underworld. Matching Maxxor in Courage and far surpassing him in Power is Chaor. Though only able to wield a single element of Fire, he has an additional Mugic Counter to tip the scales in his favor. Chaor is capable of matching Maxxor in a match anyday.
The Second-Greatest Threat to Chaor, Second-In-Command of the Underworld. Lord Van Bloot punishes creatures with low Courage by reducing their Energy significantly. Combined with the Earth Element and Power that makes Chaor look weak, Lord Van Bloot is one of the greatest, If not THE greatest, Creature of the Underworld.
The One Linked to the Cothica. Heptadd is the Ultimate Muge and Elementalist. He is able to cast Mugic from ALL the Tribes and has a grand total of all four elements. Fire, Air, Earth and Water. His diversity makes almost any attack he does, deal the maximum possible amount to the opposing creature.
FUN FACT: Out of All the Big 4, Heptadd is the only one with a PROMO or EXPO version... And the only one without a "Remake".