The Behemoth is a Hero with high HP and Defense stats. His attack rating is slightly lower then the Berserker. When using the Behemoth, he has the lowest attack range out of all of the other Heros (just a range of 1, meaning melee range) but as mentioned above, compensates for a massive HP pool and defense. The Behemoth is able to attack two targets at once, providing that both are within range of the Behemoth.
The Behemoth's unique medal is the Earth Medal, which allows the Behemoth to take more hits. For each level added on the medal, he gets 60 additional hitpoints and 1.2% resistance against debuffs.
The Bhemoth's ability is , in which he will smash the ground in front of him with his weapon. This will cause a set amount of damage (which increases as you improve it), having a similar effect area to the smashing spells and will cause the Dizzy effect to take place regardless of the targets hit.
You can find more about Behemoth Items here.