Regarding the plague tent – I think the skill isn't very useful, and it's also weaker compared to the ballista. If you max out "rapid fire" on the ballista, you get one shot for the "ballista" skill and one shot for the "rapid fire" skill. But with the plague tent, after learning "plague tent," you have to take the "tent" skill, and when dealing damage with the tent, you don't get anything from the "tent" skill. In other words, two interchangeable skills can't work simultaneously, so I discarded the plague tent.
Блистает там воздушностью прогалин.
Но между кедров, полных тишиной,
Расщелина по склону ниспадала.
О, никогда под бледною луной
Так пышен не был тот уют лесной...