FS High Priest Guide by Heysus

Essentials:
-Common auto skill slot knowledge
-Patience
-Effort
-Sacrifice

Stats (RAW):
-99 INT
-99 VIT

Skills (Base):
ACOLYTE
-Heal 10
-Kyrie Eleison 10
-Blessing 10
-Increase Agility 10
>TOTAL 40

PRIEST
-Impositio Magnus 10
-Magnificat 5
-Gloria 5
-Sanctuary 10
-Resurrection 3
-Aspersio 2
-Clearance 5

HIGH PRIEST
-Safety Wall 10
-Angelus 5
-Assumptio 5
-Lex Divina 3
-Lex Aeterna 1
-Jud 1
-Suffragium 5
-Meditatio 10

Equipments (RICH) with explanation:
Weapon - Croce Staff III (minimum +5 or above)
--Why +5? For that extra 20% heal, remember that it has 4% increase heal and sanc for every refine so go for the optimal 20%.
--Why tier 3 only? Because you need only INT my love.

Offhand - Royal Silver Shield II
--Best defensive offhand in game and it will greatly provide that additional HP pool and def if upgraded to tier II.

Armor - Holy Robe III
--The best armor. 5% heal increase because of the set effect with Croce Staff. Additional INT, additional SP, SP cost of your major buffs are lowered which is important especially for KE. Additional INT for increase heal if tiered to III.

Garment - Staunch Mana Manteau III
--No need for tier IV as the effect is useless if you can't achieve +10, not worth doing though. 

Shoes - Staunch Shoes V
--Tier V for max HP benefit and shorten casting time due to garment combo.

Accessory - Eye of Dullahan III x2
--Why not IV? Because again you only need INT. Will add MATK due to staff combo but it won't help heal. Greatly help for Jud.

Upper Headgear - Crown [1] or Tiara [1]
--INT baby!

Middle Headgear - Elven Ears
--INT and additional MATK for Jud

Lower Headgear - at this point, anything that suits you!

Tail - at this point, anything that suits you or aim for Devil Wings for MATK.\

Card (Assuming that you only have the basic set and did not max out slot):
-Weapon (Draniliar Card) - INT and MATK
-Upper Headgear (Marduk Card) - Prevent silence

How-To:
  1. Heal is affected by INT not MATK, even if you have 9999 MATK, it will not increase the amount of your heal.
  2. No need for DEX as the Staunch set will provide the same casting reduction (maybe more) if you have 30 base DEX.
  3. VIT is your main shit as this will determine your lifespan.
  4. You need blue gemstone, like shit tons of it for Safety Wall and Resurrection.
  5. Why didn't I maxed out Resurrection? Because level 3 has an instant casting time whilst providing a great chunk of revive HP which is almost similar with the level 4 one that has a longer casting time. 
  6. Runes? Focus on Holy Damage increase as it will increase heal, also your priorities are Lasting Heal and Lasting Heal % increase, Multi Heal, Impositio Magnus and Kyrie Elieson. The rest, go for MATK boost for Jud.
  7. How can I solo level up? Stick with Jud and pump your MATK. You can't switch to Nemesis Staff because you won't benefit much from it since you don't have LUK on your stat. LUNATIC PET IS DE KEY!
  8. Use auto skill slot even if you are doing manual support, put Heal, Kyrie Elieson, Clearance and Resurrection.
  9. Learn to use Stay Alert.
  10. Look for INT and MATK enchant.
  11. Collect cards and headgears that will increase your INT and MATK in your adventurer book.
  12. If you're alive, everyone will survive so don't forget to hotskill those transformation scroll for emergency use. If your heal can't keep up with the damage, use it, full HP, no ailments, turn back to normal self and viola, full HP again.
Final Question?
--How strong is your heal count if you follow this? Since Bacsojin Card is still out of reach, you can get a decent 5k-6k+ heal bomb and 2k-3k / tick sanctuary.