Yoel of Londor Dark Souls III Guide
Last update: 11 May 2016
Yoel can be met in Undead Settlement. Walking between dead characters (opposite the first gate, near the abyss) you can hear one of them. In fact it isn't dead and you can find Yoel of Londor (see screenshot). If you let him join you, he will teleport to Cleansing Chapel.
You will find him in the lower part of the chapel. From Blacksmith Andre move forward to Greirat and turn left - there is a hole behind the stairs. Yoel will offer Call over gesture during your first conversation and will trade spells later on.
However, the most important feature of this character is that he offers you 5 "free" level ups. Talk to Yoel in order to "unleash the true power of your character". You will level up, but at the same time you will be marked with Dark Sigil, which will be added to your inventory. Hollow level will increase with each death.
The first level will be reached right away but further ones will require hollow level (you can check it in your "Status" options). 2, 6, 12 and 16. Each death will increase the hollow level adequate to the amount of Dark Sigils. Thus you need to die twice each level (except the last one), to use Yoel's ability.
When you use his ability five times, Yoel will be replaced by Yuria, but only if you cured yourself from Dark Sigil at Fire Keeper.
Yoel and his questline are related to one of the endings.