Holy Wars make alll party members invincible
Heros make 1 person invincible (mwahahahahaha)

just get the laguna card from Ellone and refine it to get 100 heros
change 10 into 1 holy War
even 1 holy war is enough

Draw Meltdowns from:

Bomb
Gayla
Elastoid

yes mystery fluid refines into meltdowns

(SPOILER)U can also get meltdowns in ultimecias castle...art gallery