One of the many things I really like in Cairn is Critical Damage. From the Cairn 2E Player's Guide it is as follows:

Now that's all well and good, but lets zoom into an almost throw-away line right at the end:

There is very little guidance about what this Critical Damage ability should look like, but most monsters in the bestiary have one and the Warden's Guide simply says:

Here are some examples of Critical Damage from the bestiary:

Creeping Vines: Target is pulled into the air where they asphyxiate within a few minutes. 
Ghost: Target must save WIL or is possessed, acting only on behalf of the ghost’s whims.
Mind Lasher: A tentacle rips the victim’s brain out of their skull.
Vampire: The vampire drains the target’s essence, dealing d12 damage to WIL. If the target reaches 0 WIL this way, it dies and is raised as a thrall of the vampire.
Water Elemental: Target is enveloped by the water and drowns in three rounds.

These are great and give each monster their own unique flavour by playing into what they are or what they can do. Besides a few exceptions, they are mostly describing how they kill your character. While designing my own monsters in my Cairn forest depthcrawl, Downrooted, I kept wondering if Critical Damage abilities could be more than just a flavour of death. What if it could be a form of lateral character advancement. If hit with Critical Damage and you somehow survive, you should be changed in some way; gaining a unique hindrance, becoming more powerful, or both. 

Obviously Cairn has scars, which is kind of like this but more general. You reach exactly 0 HP and you get a scar that can make you stronger. I am not talking about stat increases, though. I am talking about physical changes, new abilities, things that change how you play your character, things that can be advantageous if used the right way, etc. Let's take a look at some of my examples: 

Shaper Husk: Liquid metal fills the target's wound and quickly solidifies, taking up an inventory slot. The target gains a permanent +1 Armour.  
Crocotta: The crocotta locks its jaw around the target’s neck and steals their voice. The target cannot speak until the crocotta is killed.
Bramble: Wooden fingers pierce the target's flesh, planting a plethora of seeds deep within. The seeds will sprout within a week and grow into leafy branches within a month, after which the target can spend an hour basking in the sun to remove the Deprived condition. 

I deliberately decided that none of these abilities would cause extra damage or out right kill the target. They are all things that change the character in some notable way. The victim of the Shaper Husk is now fused with metal, giving them extra armour at the cost of an inventory slot. The Crocotta target will never be able to speak again until they hunt it down and kill it. Now they have a quest. Lastly, the Bramble target can use photosynthesis to get energy and food, but are basically a walking shrubbery unless they prune themselves. 

Going forward, I would like to make more monsters that use this design philosophy. It could be greatly explored as the focus of an entire adventure or potentially a hack of Cairn itself. But until then, please help fund my current game, Downrooted.  

The funding will go towards hiring an editor to get the game the polish it needs. Why does it need to be polished? Well, I want to get physical copies out there in the real world. Alongside the polish, there will be more art, a layout refresh, and a few big exciting changes I'll talk about later.

So, if you like what I do, please consider contributing to the campaign or sharing it around with people you know. 

If you have any questions you can drop a comment or DM me on Bluesky.