Can someone explain me how stun works in Backers Build 4? I’m testing it and I can’t figure it out. I though that most likely it is triggered when you deal stun damage higher than current HP of creature. But sometimes it works when I deal stun damage lesser than current HP of alien. In last battle I have dealt 19 stun damage with Hel Cannon to creature who had 20 HP after being hit and it was stunned. So I though that maybe you need to deal more stun damage than some portion of max HP of creature and that maybe treshold is set at 50% or 30%. For example Mech Arms doing 18 stun damage don’t stun sirens, but Hel cannon can do that dealing more than 25 stun damage. Btw Mech Arms which attacked Chiron who had 38 max HP did the work correctly, but he also had then 17 HP left after being shot. It would be true for almost all enemies hit by Hel, but also in last game my Hel Cannon did 90 stun damage to the queen, which was lke 60% of her max HP, and she was not stunned. So last assumtion is not true unless queen is immune to stun like vehicles are.
One more thing, if you are a lazy bum as I was and didn’t read the manual.
‘Stunned’ is not a disable for a turn or two, but 75% AP loss. If you are a brave guy without an ammo, so you charge a crab to stun him with a melee. You can stun him. and then get hit next round…
Yeah, because their pincer attack is for 25% of TU. 
Only melee crabbies have such low cost of attack. Every other alien needs 50% or more. Except fireworm and mindfragger which use 0% attack.