Random Attack Damage - I want to make bears/wolves/lions have potentially deadly attacks

[LordStark]

I was wondering if there is a way for me to vary the damage done by wild animals so that when you send one of your units up against them there is a slight risk that you will be killed outright. 

The idea is that on this map I am making the northern Lord lives in a harsh climate with many dangerous animals. It means that his troops (the ones that survive animal attacks) will have better experience than the southern lords who have an easier time getting food from fruit bushes and higher yield farms.

[Stan`]

There is no critical damage feature but it could be added by modding attack.js.