First you have to head towards the Third Church of Marika in Limgrave. It's situated east of the first few Sites of Grace Elden Ring Runes. From there, you need to head northeast until you reach an entrance that is surrounded by water. It's actually part of another quest will give you a character later on, although it's not necessary to meet them first.
The portal takes you to Greyoll's Dragonbarrow the high-level area located to the north of Caelid where you can find one of the game's most odd characters, who you'll see immediately behind you once you arrive, along with an opulent site. Beware of the massive beast on the staircase in front of you as leaving, as you won't want to mess with it.
Outside, there are small, relatively weak enemies along with an archway with another place of grace adjacent to it. Grab the site of grace however you'd like but don't go over the bridge. Instead, continue to the little enemies because they'll be farming.
They're quickly. While magic builds can be beneficial here, melee character can stagger them and employ stealth. The video says you'll earn 637 runes in each kill and there's several however after testing it I found I was actually getting much higher: 1094 runs per kill. The nearby site of grace will allow you to keep respawning these runes. Just don't give them an opportunity to strike, as they could kill low-level characters during a hit.
Since you're already in Dragonbarrow anyway, you might as well hit up another cheesy farming spot nearby cheap Elden Ring Items. This one comes from TagBackTV on YouTube and there's no need to engage involved in any battles to replenish your rune jars.
