Disgaea 5: Alliance of Vengence - Netherworld Effects FAQ by aces4839

Netherworld effects have various different effects depending on which one you
choose by first defeating stray Lost armies in the Item World while having the
Invaders route selected for higher chances. You can then talk to Meaver behind
the Dimension Prinny to customize the effect you want to have. To use the 
effect, your Bonus Guage must be at least 1, then you can open up the battle
menu by pressing triangle and Summon NW. Below is a list that you can get from
the stray Lost armies and effects each one has:

1. None - None
2. Sandstorm - Decrease accuracy by 20%.
3. Fire Powder - Decrease Fire Resistance by 50%.
4. Snow - Decrease Water Resistance by 50%.
5. Gale Force Winds - Decrease Wind Resistance by 50%.
6. Group Activity - Increase stats of the unit with the most influence. This 
means that if the number of dispatched allies is more than the number of 
enemies on the map, all stats of your allies will increase by about 10%. The 
same is true if there are more enemies than allies on the map.
7. Bounce - Everything will bounce when thrown.
8. Final Trump Card - Boost all allies, but lose the next turn. This means if
you end turn, no matter what happens even if you kill all enemies, it will 
trigger a game over.
9. Bonus Costs - Boost all allies, but the Bonus Guage won't fill.
10. EXP Up - Increase amount of EXP gained by 50%.
11. Mana Up - Increase amount of Mana gained by 50%.
12. HL Up - Increase amount of HL gained by 50%.
13. WM Up - Increase amount of Weapon Mastery gained by 50%.
14. Skill EXP Up - Increase amount of Skill EXP gained by 50%.
15. Class Prof Up - Increase amount of Class Proficiency gained by 50%.
16. Netherworld Drop - You can use the Netherworld Drop skill once. This is 
needed for one of the Other Skills at the Data Shop.
17. Total Geo Break - You can use the Total Geo Break skill once. This is also
needed for one of the Other Skills at the Data Shop.
18. Fire Providence - Increase Fire Resistance by 50%.
19. Water Providence - Increase Water Resistance by 50%.
20. Wind Providence - Increase Wind Resistance by 50%.
21. Elemental Barrier - Increase all elemental resistances except star by 10%.
22. Fast Walk - Increase mobility by 1.
23. Hop Around - Increase jumping power by 10.
24. Strong Arms - Increase Throw Range by 1.
25. Relief Support - Supplies will be provided at end of turn.
26. Auto HP Recovery - Recover 5% HP at end of turn.
27. Auto SP Recovery - Recover 5% SP at end of turn.
28. Auto Healing - Recover 2% HP & SP at end of turn.

That's all of them. If anyone knows any more effects, send me a message or 
make a topic at the boards. I will update as necessary. Have fun hunting for 
those effects! Thanks to NIS and everyone involved with this game. It's been 
quite enjoyable.