Gabriel Celeste is the second to last boss of a secret dungeon called the "Seraphic Gate". You will find Gabriel on the third floor, there, guarding a "Teleportation Orb" to the fourth and final floor. When you reach her, you see that he is an angelic being emitting a blue aura with three pairs of wings. Hench the name "Serpahic" Gate; "A celestial being having three pairs of wings". Gabriel has both masculine and feminine aspects. Thus, her appearance is that of a women, with long blond hair an a halo above her head. He is wearing a flowing black dress and holds a crescent moon staff in her right hand. Her masculine aspect comes from her voice, which is much deeper then what you would expect for a woman's voice.
When you reach Gabriel he declares: "...A human? No, a frightening and might spirit body. And it is from another world... Hah! Perhaps humans who label all they cannot understand as "supernatural" would think you a god... To me, however, you are mundane... But I am interested in you. So, will you fight me, then? Though this will be a very short fight!!". Obviously, Gabriel thinks Lenneth won't be able to last long in a battle with her. Although, he is right, because the first time you fight her, depending on your party's level and equipment, the battle can take upwards of fifteen minutes. Those playing on Easy or Normal mode will have a much harder time then those playing on Hard mode, this is because you will not have access to the majority of the secret weapons, equipment, and characters as those playing hard mode will. Those playing hard mode, will have a much easier time, that is, assuming that acquired the eight Flame Jewels from the main game needed to unlock the eight secret doors located around the Seraphic Gate.
As the battle starts Gabriel will begin by saying: "Vulgar beings, you have not known true terror repent!". He then uses "Empress Massacre", a twenty-eight hit attack that is very impressive to watch and will deliver around 299,075 damage to one party member. In order to win this battle, you will need items like "Angel Curio" and skills like "Guts" and "Auto item". Your goal here is to keep the damage up while reviving your team members quickly. No healing is needed. As long as you can keep this up, and your item supply holds out, you will win, even if it does take a fair amount of time. Take note every ten turns ten turns Gabriel will cast "Meteor Swarm". This attack will inflict about 367,773 damage to everyone in your party.
After Gabriel reaches zero life he will begin to fade away uttering: "I have been defeated well done heroes... I am sure we will meet again in another time and place...". Congratulations on besting Gabriel Celeste! You now have access to the final floor of the dungeon, but the true test of the Seraphic Gate is yet to come.