I believe there is also a defensive building that does damage to attackers 

Sublustris wrote:

This does looks like a preemptive bombardment. Do you have a save to reproduce the issue?

P.S. On a second thought, isn't this an effect from Gnashast population bonus?

Is it? Where do I find information on that? I can't see any details on this happening in the screen right before the battle. I don't have any of them in my population yet, so I can't check if it's their population bonus. :(

It's probably just the recently changed "Tractable Armaments" improvement. It currently does "+750 damage to attacker during ground battle", just like preemptive bombing.

jokano wrote:

I believe there is also a defensive building that does damage to attackers 

SirBagel wrote:

It's probably just the recently changed "Tractable Armaments" improvement. It currently does "+750 damage to attacker during ground battle", just like preemptive bombing.

I see, that makes sense. Is there any way at all to see its effects written down before the battle starts? Because, as you can see by the result of my blitz here...

The enemy ends up shooting the ground just to make me feel better. :/