Slitherine

So I was asking myself what was the most cost efficient (ork) unit to kill reaper titans and noticed that I still have no idea when wounds really happen and when they do not.

I would assume that a shot/swing hits its target so I am not looking at cover, distance accuracy ratings. When does this shot wound and when is it deflected/absorbed by the armor of the target? It certainly depends on the 2 weapon values strength (WS) and armor penetration (AP) as well as the defense (TD) of the target. I was searching through the forums and found this information:

Xandie wrote:
Chance = (50+(weapon.strength - target.defence * (100 - weapon.armorpenetration))
You should note that if the weapon.strength is 50 points smaller than target defense (assuming armor penetration of the weapon is 0 and target hexfield doesn't grant a defense penalty) the weapon won't be able to put a scratch on the target, regardless of how many times you shoot.

I think the second part should be right as that is what we see in game easily (shootas will never scratch a 95 defense dreadnought no matter how many shots they take). However, the formula seems to be wrong. You will always get negative values out of it.
I think it should be more like this:
Wound chance = 50 + WS - (TD * (100 - AP) / 100)
This way the AP basically reduces the TD by its percentage. After that it is just a comparison of the new Defense and the WS+50. That would explain why shootas (in WS/AP/TD - 35/10/31) can never penetrate the dreadnought armor of 95. The chance of wounds is -0.5%. However they are able to wound a Landraider with “only” 90 TD. Chance is 4% here. (still not accounting the number of shots taken and the accuracy).

I would love it, if anyone could tell me rather this is correct or not.

Yeah, i guess you are right. Would be interesting to know the chances for different damage values depending on the difference between attack and defense as well.
Best ork unit to kill a reaver is tankbustas in melee ofc. Another semi decent one is deff dread with kill saw in melee, but it cost 5 times as much and deals about the same damage. Kinda don't like that tankbustas is the only decent anti-vehicle unit for the orks, all these kill krushas, skullhamas and kill burstas that supposed to be good against vehicles usually do 1-2 damage due to abysmal accuracy and die to return fire from anything with the same range.

Yeah, exactly that is the conclusion I got to. Tankbustas are best.
I thought lootas might work since they have not 20% but 30% AP. But with the formula above I came to the conclusion that lootas have a wound chance of -1 so they cannot scratch it due to the low 40 WP.
Tankbustas have chance to wound of 21% range and 48% melee which is pretty nice. However, that only works if you get close to the reaver titan. If you cannot do that, the best way seams so be gunning it down with a stompa with belly gun or even a Gargant. Both are cost effective even though not as cheap as tankbustas.

Would be interesting to know the chances for different damage values depending on the difference between attack and defense as well

If I am not misstaking, that would be a 3D diagram. If I make one later, I will post it here.

Another thing: it is possible to get to wound values over 100%. Does that mean I could kill 2 health (like 2 grots) with one shot?

FuFuHunt3r wrote: Another thing: it is possible to get to wound values over 100%. Does that mean I could kill 2 health (like 2 grots) with one shot?

I think i read somewhere that one attack can only kill one "strength", so shadowsword's volcano canon can kill one full health gargant in one of it's shots but not two gretchins... Though i dobut that it deals, say, two damage if chance to penetrate is 200%, otherwise it'be impossible to oneshot gargant with shadowsword.

I think you misunderstood the first formula, the 100 is supposed to be 100% - AP%, which is the same thing as yours (least if I'm reading your acronyms right). Lootas have -1% chance in both

The ork tank with thew belly gun tends to do fairly well, not the best but an annoying unit.

The chance for scoring higher damage than 1 is random, but usually occurs if there is a large advantage to wound, larger the advantage the more likely to do more damage. Volcanno cannons usually do 2 damage/shot min because of this. You can do up to 4 damage/shot, and then instead of 5 damage it is an instant kill (for that unit strength). That said, one shot=max one unit strength dead, no one shot, two kills.