Okay. Let's take a baseline of a Hume BLM/SCH 99 with capped job points. This gives 110 INT, +90 MAB, and +43 MDMG as base stats. We'll throw in Idris Acumen and INT for another 45 MAB and INT.
Regarding target monsters, level 123 Hippogryphs in Reisenjima have 251 INT, while level ~140 Dvergrs in Inner Ra'kaznar have somewhere around 400 INT. As a compromise, let's say the target has about 325 INT. The mob's MDB and elemental affinities don't matter since they're purely multiplicative. Weather and Day are ignored other than assuming they're active for the choice of waist.
For non-visible slots in gear, I'll take a generic high level BLM set, using R15 Marin Staff +1, Enki's Strap, R15 Ghastly Tathlum +1, R25 Sorcerer's Stole +2, Malignance Earring, Barkarole Earring, Freke Ring, Shiva Ring +1, a 10 MAB/30 INT/20 MDMG Ambu cape, and Hachirin-no-Obi. In total, including buffs, the player will have +239 MAB, 288 INT, and 309 MDMG without the Mallquis/Agwu. This results in:
5/5 Mallquis +2 (including set bonus): +314 MAB, 548 INT, 569 MDMG
5/5 Agwu (R0): +414 MAB, 480 INT, 409 MDMG
5/5 Agwu (R20): +514 MAB, 480 INT, 419 MDMG
Thunder VI sadly does not have documented information, so we'll be using Thunder and Thunder V as test spells.
Thunder, Mallquis +2: (85 (base Thunder factor) + 100 (dINT factor) + 569 (MDMG factor)) * 4.14 (MAB Factor) = 3121
Thunder, Agwu (R0): (85 + 100 + 409) * 5.14 = 3027
Thunder, Agwu (R20): (85 + 100 + 419) * 6.14 = 3708
Thunder V, Mallquis +2: (900 + (4*50 + 3.74*50 + 3.75*100 + 3*23) + 569) * 4.14 = 9522
Thunder V, Agwu (R0): (900 + (4*50 + 3.74*50 + 3.75*55) + 409) * 5.14 = 9777
Thunder V, Agwu (R20): (900 + (4*50 + 3.74*50 + 3.75*55) + 419) * 6.14 = 11741