Could someone explain how the suffering mechanic works exactly? I know it has to do with the spell Mutilation, but the stacks on me don't seem to be appearing consistently or sometimes they disappear when my turn starts. Same with bleeding but I think that has to do with my using life drain spells that remove stacks.
It is literally checked and set whenever you lose or gain life - if you used healing or life steal, you may lose Suffering, if you take damage - be it directly, or from a poison/DoT condition like Mutilation or ap/mp poisons, you may gain it. Also, note that Suffering is, as mentioned, ~10% missing life. Mutilation take 10% of your current life (roughly) - meaning it does less damage every turn if you aren't also healing it back. While this reliably gets you to suffering 2 or 3 (since your enemies are "helping," as well), it isn't so reliable when you get down to Suffering 5+, since it's only going to be doing half the damage or less. It's still handy, since it also grants a Power buff to you while it's engaged, and can stabilize healing from your sword or spells so you can maintain your Suffering - just don't depend on it exclusively to get to 8-10 Suffering (not that you should be - taking the risk of 10 Suffering is rarely the best answer in a fight, except as a finishing blow)