Start by talking to Kaqemeex at the Taverley Stone Circle. Ask about Druidic Ritual, and ask what he needs help with. He directs you to Sanfew, who is researching a potion to offer to Guthix.
Speak to Sanfew in the southern house on the east side of the river. He asks you to obtain a vial of untainted living water, wandering wyrmwood, and scales from a stone fish.
Head south of Taverley, around the lake. Look for the wyrmwood in the area, and when one gets up and starts wandering, try to pluck some leaves. After you get the leaves, head to the lake side and look for the sparkling fishing spot. Reel in a stone fish, then get scales from it using a chisel.
Finally, head into the Gelatinous Abomination Cavern located in the middle of the lake. Talk to Ariane, and she will follow you through the cave. Head all the way south into the cave and you will come across Magic Stick, a large troll. Pick up the mindspike staff and speak to Ariane again.
Fill up a vial with the untainted living water, then return to Sanfew.
Give the ingredients to Sanfew, and he will mix them into the Ointment of imbalance. Return with the potion to Kaqmeex at the stone circle. They will perform the ritual and their prayers will be answered.