Spoiler Warning: Details about significant plot developments follow. It is recommended that you not read further into this section until completing the quest “Wrath of the Bear God” at the end of the game’s first chapter.
In Mask of the Betrayer, it is possible to become a spirit-eater, an affliction that makes your character more powerful, but at a cost. A spirit-eater develops a thirst for spirits and souls. Without a steady diet of them, its power wanes, and it must seek out opportunities to devour spirits and be restored.
Spirit Energy
A spirit-eater subsists on energy gained from devouring spirits and souls. Over time, that energy is consumed, and must be replenished, or its health will begin to decline. Your spirit energy will be displayed to you in the form of a bar on which you can monitor its status. Watermarks on either side of the bar denote points at which you will enter a new stage of health impairment should your energy drop below them. The progress to new stages accelerates as spirit energy drops, and each of them may mean new penalties to statistics, status impairments, or hit point damage over time. The final stage, at the very bottom of the bar, means death and the end of the game for a spirit-eater character.
Craving
The more inclined to embrace its hunger and devour spirits that a spirit-eater is, the more it will begin to crave them, and become dependent upon them. Conversely, a spirit-eater that tends to fight for control over its hunger will find that it is progressively able to subsist on fewer of them. Just below your spirit energy bar is a horizontal bar that displays your present level of craving. Its level is influenced by what spirit-eater powers you decide to use, as well as particular decisions you make along the game’s storyline. The more full the bar, the more consumed you are by your hunger, and the faster your spirit energy will be depleted. However, frequently giving in to your hunger may also cause you to manifest certain new spirit-eater characteristics, and those characteristics may be to your benefit...
Powers
A spirit-eater gains a number of powers, which he can use to manage his affliction, improve combat, and manipulate souls for use in crafting.
Devour Spirit
• Limitations: 10 uses/day. Each use after the first causes a significant increase in craving. 5-minute cooldown. May not be used on the same day as Suppress. • Description: Causes a fixed amount of damage to a target, replenishing your spirit energy and staving off your affliction. May be used only on spirits - elementals, fey (such as telthors), and incorporeal undead (such as wraiths or shadows). Killing a target with this attack confers a sizeable bonus to your spirit energy and yields a valuable spirit-based crafting essence.
Suppress
• Limitations: 1 use/day. May not be used on the same day as Devour Spirit, Devour Soul, Spirit Gorge, Eternal Rest, or Ravenous Incarnation. • Description: You suppress your urge to consume spirits and regain a small amount of spirit energy. This also reduces your level of craving. Suppress shifts alignment toward Lawful and Good. (The v1.11 patch will remove the alignment shift.)
Satiate
• Limitations: 1 use/day • Description: At the cost of XP, you feed upon your own spirit to fully recharge your spirit energy.
Provoke Spirits
• Description: You reveal the nature of your supernatural hunger to spirits in a radius around you. Any neutral spirits within that radius will turn hostile and attack you, thereby making them susceptible to being devoured.
Mold Spirit
• Description: You gain the ability to use spirit-based crafting essences gained from Devour Spirit in special new crafting recipes. • Where / How: Act 2 in Lienna's secret room in the Shadow Theater. When returning to the veil you will receive a key from Magda opening another door in the shadow of the veil. In that room is a clay golem. Reach into the clay golem and remove his heart. Use your spirit powers to "activate" the heart and put it back inside the golem
Malleate Spirit
• Description: You refine your ability to work with spirit-based crafting essences, and are now able to use recipes that feature any grade of spirit essence. • Where / How: Act 2 in the Academy of Shapers and Binders. Use the odd box item on a spirit essence.
Devour Soul
• Limitations: Costs 1 use of Devour Spirit. Each use after the first causes a significant increase in craving. May not be used on the same day as Suppress. • Description: This is the same as Devour Spirit, but can be applied to humanoids as well as spirits. • Where / How: Act 2 at the Wells of Lurue. Complete the Hill Tribe quest at the Wells of Lurue by doing what they ask you to. You can tell the two enthusiastic younglings in the berserker lodge that the Hill tribe is a good place for them to train.
Eternal Rest
• Limitations: Costs 1 use of Devour Spirit • Description: You perform the Devour Spirit effect on an undead creature, feeding upon the negative energy that animates it. This ability causes no craving. Eternal Rest shifts alignment towards Good. May not be used on the same day as Suppress. • Where / How: Act 2 in Shadow Mulsantir. Put the Myrkulite high priest at the furnace in the Back of the Crematorium to rest.
Spirit Gorge
• Limitations: Costs 1 use of Devour Spirit. Each use causes a significant increase in craving. May not be used on the same day as Suppress. • Description: This has the same effects as Devour Spirit, but with an area of effect. If you possess the Devour Soul ability, it also gains area of effect. Spirit Gorge shifts alignment toward Evil. (The v1.11 patch will remove the alignment shift.) • Where / How: Act 2 in Ashenwood. Devour the Woodman - if you have Okku with you, you have to fight him.
Bestow Life Force
• Limitations: Friendly targets only, cannot be in last stage of affliction. • Description: You fully heal your companions using the spirit energy you have stored. Bestow Life Force shifts alignment toward Good. • Where / How: Act 2 in Ashenwood. Heal the Wood Man.
Ravenous Incarnation
• Limitations: Costs 1 use of Devour Spirit. Each use causes a major increase in craving. May not be used on the same day as Suppress. • Duration: 1 round/level • Description: You take on a terrifying form and gain damage resistance as well as a powerful attack that can siphon spirit energy from those it hits. Ravenous Incarnation shifts alignment toward Chaotic and Evil. (the v1.11 patch will remove the alignment shift.) • Where / How: Act 2 in the Academy of Shapers and Binders if you choose to devour Myrkul.
Spiritual Evisceration:
• Limitations: None • Duration: 1 round/level • Description: You are able to slay and devour the soul or spirit of a target instantly, irrespective of that target's current health. • Where / How: Act 3 by devouring the Faceless Man in the final battle of the MotB campaign.