--- Act III spoiler warning ---


1. Dragon doesn't qualify as "large monsters"?
It all started when I realized that the bonus damage against large monsters was not being applied to the dragon. So I thought maybe Deithwen was bugged, so I tried using Zerrikanterment instead. Still the bonus (4%) was not applied.

2. Damage(s) inflicted by the dragon
I am specializing in alchemy and I have a 25% boost in armor while potions are in effect. However I am seeing 2 sets of value in the combat log when the dragon hits me. One set is a lower raw damage deducted by the proper/boosted armor value. The other set (which is missing the sword and armor icon in the combat log) has higher damage (ranging from 1.3x to 2x the lower damage) deducted by the un-boosted armor value. Interestingly enough, the latter is the one that is applied. Any idea what is happening here?

3. The fiery breath of the dragon
I experienced 4 types of situation here:
a) 300+% incineration resistance (due to Virga): Never get incinerated. The dragon breath heals (way more than Gadwall + Swallow).

b) 145% incineration resistance: Incineration still occurs even though res is > 100% (every time upon contact with the dragon breath). However upon using Quen, the dragon breath heals instead.

c) 100% incineration resistance: Incineration occurs just like 145% case. Upon using Quen, the dragon breath does zero damage.

d) 75% incineration resistance (by taking off Elder Blood Trousers): Incineration occurs just like 100% and 145%. The accumulated damage over time is no different from 100% case. However upon using Quen, the dragon breath does a tiny amount of damage (probably less than 5).

Note: Quen prevents incineration from happening altogether.

In summary, I am pretty confused about how the incineration resistance works.

4. Some asides:
a) I found out that the ability David do not add 10% bonus damage against large monsters per se but it seems to merely multiply your sword's bonus damage by 1.1. So if Deithwen has +25% bonus damage, your effective bonus damage will now be +28% as shown on character screen.

b) I applied damage-boosting oil (Farka / whirl) and whetstone to both swords and do not see any increase in damage from the combat log. The oil/stone worked fine when I applied them to steel sword though. This is weird because I remember using brown oil on my silver sword in Act 1.

Any comments/ideas?

I haven't seen anyone do an analysis like this before. I did a different kind of analysis that didn't use so many specific numbers, but you come to the same conclusion I did: The alchemy tree is exceptionally unreliable, especially when it comes to boss fights.

I hated fighting that dragon so much in my alchemy playthrough.

I have a feeling you want every combat in a game fall into some sort of mathematical formula and make perfect sense... where every single game master resource out there for every single role playing game says (with no exception and usually on page one) says that:

RULES < STORY

Of course I do not dismiss a possibility that you are discovering bugs from an incorrectly applied bonuses or damage effects (with any set of complex rules it is quite possible) what I am wondering however is... was your experience in the end any less fun?

No it does not detract from my enjoyment of the game. I just like to study the mechanics of the game and stumbled into these few things that eludes reasoning. I was wondering if anyone has insights into these matters, esp. regarding point #2

Oh, being healed by dragonfire might well be a bug -- I can see how extreme resistance turning into absorption might have been overlooked.

Maybe .. but there's a way to test this.

Doesn't the mongoose potion give you 10,000% resistance to poison or something silly?
Going to deliberately get hit by the kayran spit and see what happens.