Welcome to ZMI Runecrafting!
1. Requirements
tl;dr Turn on Lunar spell book
2. Gear/Inventory
tl;dr Full Graceful + Giant/Large pouches
3. Walk-through
NOTE: Make sure your Prayer and Run Energy are full!
Spoiler
Step 1- Use the "Ourania Teleport" in the Lunar spell book (no runes req.) or The Teleport Wizard (Skilling->Ourania Altar ZMI)
Step 2- Follow the green path to the ladder.
Step 3- Go down the ladder.
Step 4- Pray ranged and run until the end, you will see the altar.
Credits: @
Fenrir
for thread layout & @
Lowkey
for gear picture