Well I doubt it's just that it just lasts for a second, and I landed Aero II only a few seconds after he used Mighty Guard.
Shinryu had also absorbed a couple of spells before he used Mighty Guard.
I've been trying to use fraps as much as possible when testing.
I wish it were really quick and simple to just post the actual video somehow...
Instead, here's the chat log from the video of the fight, using the moment events appear in the chat log and the timer on the video:
Code:
Me: WAR99/SCH49 + Brew, no MAB gear/atma
cINT = 999
MAB = 900 (10.0)
Target: Shinryu
tINT = 113
MDB = 70 (1.7)
Day = Lightningsday
Stone II capped D = 268 --> * (10.0/1.7) = 1576
Water II capped D = 321 --> * (10.0/1.7) = 1888
Aero II capped D = 379 --> * (10.0/1.7) = 2229
Fire II capped D = 443 --> * (10.0/1.7) = 2605
Blizz II capped D = 511 --> * (10.0/1.7) = 3005
Time Spell Dmg
--- --- ---
2:06 Blizzard II 3005
2:15 Fire II 2605
2:25 Aero II 2229
2:32 Blizzard II 3005 HP
2:36 Fire II 2605
2:46 Aero II 2229
2:54 Water II 1694 (Lightningsday)
3:00 Stone II 1576 HP
3:07 Blizzard II 3005
3:12 Fire II 2605
3:18 Aero II 1566 <-- No idea how yet, only just noticed this!
3:25 Water II 1888
3:32 Blizzard II 3005
3:36 "Shinryu readies Mighty Guard"
3:37 Fire II 2605
3:42 "Shinryu uses Mighty Guard."
3:42 "Shinryu regains HP."
3:49 Aero II 2229
3:56 Blizzard II 3005 HP
4:12 Aero II 2229
4:20 Luminohelix 529
4:22 "Mougurijin uses Tomahawk."
4:32 Blizzard II 3005
4:43 Noctohelix 1064 HP
4:58 (Shinryu starts diving)
5:01 (Shinryu wings folded in, changed to defensive stance)
5:19 Blizzard II 2103
5:34 Aero II 1560
5:39 Fire II 1823
5:49 Blizzard II 2103
6:03 Luminohelix 370
6:16 Anemohelix 744
6:33 Hydrohelix 666 (Lightningsday)
6:46 Blizzard II 2103
7:06 Ionohelix 819 (Lightningsday)
7:27 (Shinryu does a twirl)
7:30 (Shinryu wings spread out again, changed back to default stance.)
After this brew wore off, for the second time, and I died.
For the other spell values and the full calculation order, see my talk page.
(Absorbed spells are affected by MAB and MDB, but NOT affected by SDT or Resist)
Edit:
The only explanation I have for that 1566 dmg Aero II, is that Stonega IV may have given it's caster an extra 72 MDB on top of his 70 MDB, just for Aero II...
Shinryu's Stonega IV landed at 3:01, and Aero II at 3:18 was affected, but Aero II at 3:49 wasn't.
So maybe tier IV -agas give +72 MDB to the caster, MDB only for the element that's strong to the element of the tier IV -aga, and this effect lasts at least 17 seconds but less than 48 seconds (or just for one wind spell), and maybe it only happens for Shinryu?
Every other explanation is far more unlikely, except maybe because "Quick Magic" from Apocalypse atma proc'd on that cast it somehow screwed with the damage calculation...
However, the Blizzard II just before it at 3:07 was also a "Quick Magic" proc...
Edit:
Repeated tests for the theory in the previous edit haven't produced the same results. The damage wasn't reduced after tier IV -aga -- so that theory isn't correct.