Pentient can be found at Eldberg Lighthouse.
Pentient is weak against Moon Dust, Specter Oil, Yrden & Quen.
It turned out the monster haunting the isle of Eldberg and its lighthouse was a rare type of specter known as a penitent. Wherever this wraith haunts immediately becomes enveloped in thick fog and darkness - and those that wander into it usually never return. In order to defeat a penitent, one must remain in constant motion in order to avoid being struck by this agile creature, which can disappear and reappear in the blink of an eye to attack from behind. Most importantly of all, however, one must discover what keeps the monster bound to its haunting grounds - and break that bond as soon as possible.