This is the boss map.
4 bosses are spawned; Red Nirg (Warrior-like), Rellik (Archer-like), Margana (Magician-like), and Hsalf (Thief-like).
It is suggested to attack the Magician first which is located at the top platform. In the meantime the Warriors should keep the other 3 bosses busy with rush on the bottom of the map. When the Magician boss dies, head over to the Thief one. Try to seperate it from the other 2 bosses with rush.
Next comes the Warrior boss which will spawn Scarlet Phoenix and Azure Ocelot when it dies, which are quite easy to kill. Lastly take on the Archer boss, which is the toughest of all to kill as it stuns and curses you with almost every hit. It also can cast a 1HP/1MP attack on you combined with poison which causes an instant death. Be well prepared with potions and all cures.