I'm on 7th run on Seraphic Gate with my party & good sealstone with me fighting Dirna is really easy for me.
this is without P.R.E.
Party: Freya, Hrist, Brahms, & Lenneth
I haven't use all my Tome of Alchemy yet I'll use it on my 8th. run. This set-up is really perfect for me.

Freya - Attacker
Hrist - Attacker + Combination
Brahms - Attacker + Dammage Taker (Tanker since he had more HP than anyone in my party)
Lenneth - Attacker + Supporter

Pary Sealstone: Yggdrasil Blessing
Six Elements Blessing
Lifeforce Blessing
Sword Blessing
Enemy Sealstone: Sheathed Power Wrath

Equips: Freya = Head- Ether Crown
Acc.- Magic Dragon Horn x3
- tri-Emblem
Skills: Magician Slayer
Resist Magic
Fist of Iron
Toughness (don't need since she has the tri-Emblem)
Attacks: Sword Dance
Heavenly Funishment
Mobious Slide

Equips: Hrist = Weapon - Gungnir
Head - Ether Crown
Armor - Infinite Admiration
Arm - Star Guard
Legs - Ether Greaves
Acc. - Magic Dragon Horn x3
- Magic Bangle
Skills: Toughness
Pyschosama
Resist Magic
Mental Boost
Fist of Iron
Attacks: Trial of Existence
Downward Split
Furious Advance

Equips: Brahms = Weapon - Blood Murderer
Head - Ether Helmet
Armor - Conqueror's Armor
Arm - Star Guard
Legs - Ether Greaves
Acc. - Magic Dragon Horn x3
- White Loin..
Skills: Toughness
Resist Magic
Fist of Iron
Fortify Physique
Attacks: Blood Rain
Immortal Blow
Blood Chisel

Equips: Lenneth = Weapon - Demon Sword "Lavantine"
Head - Ether Crown
Armor - Infinite Admiration
Arm - Star Guard
Legs - Ether Greaves
Acc. - Homunculus Seed
- Moon Pearl
- Magic Dragon Horn x2
Skills: Pyschosama
Mental Boost
Resist Magic
Fist of Iron
Attacks: Glowing Pierce
Ptero Attack
Succession Slide

man, i don't know how you have the dedication to play through that many times. i lost complete interest after a couple times through sg and started a new game with new people a few months later when i felt like playing again. getting the angel slayer just isn't worth fighting the same people over and over again that much.

lols i feel ya, but its fun killing that bitch Dirna over and over again. =D

Definitely fun to abuse the Perfect Release system. The last thing i ever did was set up Dylan to one hit kill Dirna at 7,000,000 damage. Put up a video on youtube then packed away the game and moved onto Xenosaga 3.

you can use the tome of alchemy i believe...one of the tomes to turn all the demi shadows into crystals...sometimes you can hit all three with one crystal...make sure dirna is in the group when using it...or it will not work...also be warned that it doesnt always work...it's kinda unpredictable...but it will work instantly when it does work...