How to reproduce:
1. Open the attached project
2. Open and play TestScene scene
3. Select one of the Wolfs in hierarchy
4. Enable "Deactivate" property in Animator window
5. Unity crashes

When one triggers Deactivate property, deactivate animation starts. This animation deactivates Doom particle game object, which has script attached. In that script is destructor which deactivates other entities. And to make it even worse user chained it all.