Can you share some methods of testing bp magic dmg? I took yesterday and today just to test it, using thunderstorm (tp0) naked and hitting reive roots then slowly adding small amounts of pet: mab. The increase in dmg made it seems like pet was at 172mab (smn mastered, doing 1086 naked and 1130 with deimos collar, an increase of 4%).
Hmm, I did a little testing and indeed it's not always 40. I did some testing on rabbits in West Ron. Since the avatar is generally Lv120 for magic BPs I started with that.
Naked with Sancus+1 and Campestres (no pet augs) Grand Fall did 3942. Adding Adad, damage went up to 4125 for an increase of 4.6% from 10 MAB. Same increase you were seeing but my math tells me that means it has 116 MAB naked at Lv120.
1.0464 = (110 + x)/(100 + x)
x = MAB naked
I have 10 from merits and 36 from gifts. That puts the native MAB at about 70 which is 30 higher than I expected.
I decided to test if level had any effect on it. Totally naked is 1852 damage. With Adad, 1952. That's a higher gain, 5.4% instead of 4.6%. That suggests only 86 MAB naked, which means 40 without gifts or merits.
So it seems that Avatar:Lv+ does indeed grant additional MAB. I'll try to test all the variations and update my calculator soon.
Edit: Here are the results of the ones I tested using Adad Amulet:
Lv99: MAB+40 - 1952:1852
Lv101: MAB+43 (Nirvana) - 3081:2926
Lv102: MAB+43 (Nirvana + Campestres) - 3285:3120
Lv113: MAB+58 (Dashavatara) - 2954:2816
Lv115: MAB+62 (Dashavatara + Nirvana) - 4327:4128
Lv115: MAB+62 (Eminent Sachet) - 3091:2949
Lv119: MAB+69 (Sancus+1) - 3860:3688
Lv120: MAB+70 (Sancus+1 + Campestres) - 4125:3942
Lv122: MAB+70 (Sancus+1 + Nirvana + Campestres) - 5432:5192
It's a little confusing. The Campestres doesn't really seem to add MAB except in one case. The Nirvana only seems to add any up until the avatar hits 119 or 120, at which point MAB seems to top out at +70.