Find the Ancient Oak Treant in Kings Woods South. Its Legendary Rein unlocks a minion with a Max Health passive and the Healing Spirit ability. Those minion effects should not be confused with the boss's own combat mechanics.
Find the correct region
The Rotten to the Root achievement names Ancient Oak Treant and Kings Woods South. The Raptor and Werewolf achievements name Kings Woods, so do not treat those area labels as interchangeable when looking for the Treant.
What the Rein actually says
The Ancient Oak Treant market description identifies a permanent unlock and these effects:
| Effect | Listed behavior |
|---|---|
| Health Increase — passive | +10% Max Health |
| Healing Spirit — ability | Heals the player for 20% Max Health |
| Healing Spirit cooldown | 12 seconds |
The passive increases Max Health; the active ability heals. Do not read the 20% value as passive health regeneration or assume the ability triggers exactly every 12 seconds in all circumstances. Activation behavior and interactions with other healing modifiers are not specified by this listing.
Use it as a support comparison
This is a health-and-healing option to compare with the Werewolf's Life On Hit and attack-speed support. The Raptor instead lists damage-over-time and critical modifiers. Choose which effects to investigate for your setup; these descriptions do not establish a tested ranking.
Older Demo discussions call a Treant encounter the final boss. That does not establish the final encounter of the released game, and this Rein description does not prove how to counter a boss heal. See the boss region index and Rein acquisition limits for those separate tasks.
Steam / Windows · Checked September 30, 2026 · Written and source-reviewed by Deskrawl Guide Hub; not hands-on tested.