An advance party level 40 + with a decent some party points. Without a party you will not be able to enter the dungeon. Remember to buy a Red scroll ( Enhanced Party Scroll) this helps to increase the link damage. Make sure before you enter the dungeon and your party is full of players. Make sure you use Party Skill Stacking (Green Scroll) helps you stack skills for a while.
A Kite Tanker (A tanker that would just run around) no need to worry about HP just make sure you have enough hp. A player just needs to run around avoiding the giant while other players attack it.
Regular Tanking: Just have alot of hp estimate (800k hp+)
Main Damage Classes: Elementor , Psykeeper WILL do the best damage possible. Make sure either one has Link Attack and uses it while attacking the Boss. Holy Cross (Ringmaster's skill) and Cursed Mind ( Hero Elementor's skill) will help alot with the damage.
Don't forget to bring all the consumable buff ups.. they'll help too and most of all dont forget holy scrolls just in case of some Boss Giants effects like stunning you or you can't use magic.
Less Damage Classes: Blades , Knights, Billposters, Rangers, Ringmasters.
Note : You can bring along these classes to clear hallways of mobs or statues in dungeons. You may not need them though.
When it comes to getting good drops
Don't forget party skills
Don't forget to get lucky box awakes on your CS PET and PET (It's best to remake a pet and a cs pet that has LB awake and to swap it at the end BEFORE you kill the boss giant)
Cloak of honor adds +1 Lucky box Only 10mill (Swap at the end when Boss Giant is at little hp)
Protect ( Ringmaster's skill) Adds +2 Lucky box . So it will help if you have a ringmaster
REMEMBER Have the player with the most LB kill it don't let any other party members attack it.
That's pretty much it! This should help with all giants