oh nuke dungeon on red map.. u doing quest at there?.
that 1st boss actually not hard. he just have 1 buff (400% LP and EP leach for 1 min). if ur healer can spamming giant less then in 1 min, more easy to kill. u need ultima in ur party, to heal u from boss stunt (
http://www.dbocom.com/skills.php?id=372).
u dont need full party to there. 3 players is ok. to kill 1st boss when he cast buff, dont hit him. then back to hit him again after his buff gone.
2nd boss (grand chef majin girl) at this dungeon more easy.