You'll need to be at least 75mil PL to complete this. The requirement of the items however is 25mil base PL.
IT to Mhenlo or walk here by leaving the SE part of Hydia city. You'll find the Temple proper past the maze like forest area.
Talk to Mhenlo first. Follow his red word prompts say TROUBLED, HELP, SACRED WATER, CASK, to learn about the quest. Head into the forest and find Deios inside a Dark Cave. When you do SAY SACRED CASK then SAY LURE. He will inform you that you need to go find a Holly Leaf.
Go murder flying squirrels until you find A Golden Holly Leaf. Once you have it head to the NW section of the forest and Cerenbul will appear. He is 75m PL. Take the hide you get from Cerenbul back to the cave with Deios and get a cask. Head just south of Deios and your water cask will be turned into an even better water cask. You can drink from this cask for a regeneration buff, and also refill it when you need to. You can refill it at the waterfall or in other fountain locations in the MUD.
Head back to the young monk near Mhenlo and he'll mention needing not only a cask but some flowers. Go to the nothern section of the temple and find the room with "A great rushing waterfall is here." Workout, meditate, or hangout in this room for a while for a chance at getting a flower. You can get one while standing or meditating or whichever. You might need to have the cask. You can get multiple at one time if you'd like to sit here and wait till you have multiple. You will a total of 8 for every reward from this quest.
Once you have a lotus flower (or 8) go to Deios for a Healing Salve.
Return to the young monk east of Mhenlo, and GIVE SALVE YOUNG. Now you'll need to defeat the demon for a horn.
The demon PL mirrors so be ready for a fight. From the young monk you can speedwalk esstywrwyywwyt to get to the demon. And speedwalk back with rqeeqqeteqrnne. Once you arrive back at Mhenlo he will ask you if you value Strength, Wisdom, or Courage.
Respond with Courage : A Chain of Lotus Flowers, wrist ankle 75 armor, 1 str 1 frt 2 spd 2 spd 1% gains (can wear 4 of these)
Respond with Strength: An Amethyst Ring, finger 75 armor, str 2 spr 3, 2% gains (can wear 2 of these)
Respond with Wisdom: A Healing Ankh, neck 75 armor, 2 spd 2 spr 2 frt, 2% gains (can wear 2 of these) also a chance for a healing buff.
All require 25m base to wear.