Coril

I completely agree. On a slight change of topic, I've also thrown together a quick comparison of the Keeper weapon options. In order to calculate the whip's damage increase (which is frankly the least exciting part of the whip) I've had to include it as you would a melee weapon. In reality you'll only be getting these numbers on any turn when you get both a shooting and a combat phase, so every other turn. On top of that, I had to fiddle around with the way that the app works with the knife, since it does mortals equal to the roll on a 2+. I'm pretty sure the average for the knife should be 3.33, which is the number I've used in the calculations, but if that's wrong then so will the corresponding numbers. All in all the knife looks pleasantly surprising. Between the various other mortal wound options that we've already discussed, the knife doesn't pose an insignificant threat. The aegis is still the best option for survivability, clearly, but as a secondary Keeper or a late game summon, I could see it potentially having a place.

The issue with including both Dark Temptations and Temptation Dice in damage calculations is that your opponent gets the choice to say no to the mortal wounds. Sure, getting DP is great for us, but if you're trying to determine how good a Keeper is in combat in comparison to a Bloodthirster, then it seems unwise to include a "guaranteed" D3 mortal wounds that you opponent may just say no to when you need them. I want to make it clear that I think the Keeper is a great model that has a place in many of our lists, just that when it comes to hitting things with sticks, Khorne is the clear winner until Slaanesh devises a slightly more subtle approach...

Keepers only do mortals on wound rolls of 6s, not hits. When you calculate it on hits you get 7.5, which is probably where our discrepancy is. I agree that Dark Temptations is worth considering since it has a lot of value, but once you start including factors like that into these calculations you can start to get a slippery slope. Do we start including potential Temptation Dice damage as well?

D3+3 is an average of 5, which is what the app uses, I just simplified it because I was doing the calculations on my phone. Discrepancy could be coming from me not including Dark Temptations, maybe? I don't think it ought to count for a raw damage calculation since your opponent could always opt to give you the DP instead, which whilst potentially more powerful isn't something you can always rely on

This is the profile I'm running for the insensate thirster. I haven't read through Khorne's full book yet, but this was what was on its scroll so I've included it. In the same vein I've included the Keepers ability to get mortal wounds on 6s to wound in the calculations as well I haven't included anything like the Dark Temptations mortals (I count these as some of the many tricks the KoS have at their disposal as opposed to raw combat stats) I could probably throw together a comparison of the different Keeper loadouts such as knife and whip at some point, though

I plugged the numbers in (with a KoS equipped with the hand or knife for extra damage) and it turns out that Bloodthirsters do around about 1.4 to 1.5 times the damage of on unbuffed Keeper. Even with the depravity buff, Keeper's still get outclassed, which makes sense, I think. Bloodthirsters seem to have little value beyond just hitting things hard, whereas Keepers have plenty of other utility to bring to the table. What's interesting is that with Strength of Godhood the Keeper actually keeps up with the Bloodthirsters and even outclasses them against better saves, and that's without accounting for depravity bonuses. Lots to like with the new Keepers An interesting use of the 3d6 prayer is with the Exalted Chariot or a general with the Speed-chaser command trait. Both get mortal wounds based on your charge rolls, so the extra D6 not only lets you make charges you potentially couldn't otherwise, but also increases your impact hit output. Of course, you could always use the Paths of the Dark Prince spell for that, but something to consider

I'm not sure about being much better in combat than a bloodthirster. A KoS can be surprisingly-pillow fisted, especially when it isn't buffed or taking certain command traits/artefacts. There are upsides to the Keeper such as those you've mentioned, but raw combat capabilities aren't really among them (somewhat surprisingly imo)