Hello and sorry for bringing up an old thread.
I was curious what counts towards the kills / losses in the Causalities condition so I did some experiments. These are the results of the testing:
Every enemy, allied or own unit killed counts for the units killed parameter.
Killing allied units counts. (For example killing allied infantry with a Siege Tank).
Killing your own units counts. (For example killing own infantry with a Siege Tank).
Kills made with Ornithopters count.
Kills made with Death Hand Missile count.
Kills made with Turrets count.
You shooting / forcing the worm to sleep doesn't count.
Structures destroyed don't count.
For the units lost condition, every source of unit loss counts.
Utilizing a Saboteur (destroying a building) counts as a unit lost.
Vehicles lost to Worm Attacks count as lost.
Units lost to Spice mound bursts count as lost.
Losing a structure doesn't count.
The type of unit does not seem to affect the counters, losing an Infantry counts the same as losing a Vehicle.
