Recently I got a pretty cool idea in mind about how to handle the boss/mob dmg to surive. I think the whole process of hp washing can remain the same as how it work now(or do whatever change, just don't worsen it). Instead, change DEF and MDEF formula. So how to make this work? It's quite simple. Normally, around 5 DEF or MDEF can block only 1 dmg from the bosses/mobs. Useless AF. However, if it's changed into the formula of 1:1 (DEF and MDEF : Blockable DMG), or even 1:2 (Even more better, this is the number I suggest to change to), the whole things would be a lot better. The huge amount of DEF and MDEF on equips will no longer useless (Zhelms, HTP). Also, the buffs of 1st job warrior skill Iron body, 1st job magician skill Magic Armor, 2nd job Spearman's skill Iron Will and 2nd job Cleric's skill Bless can do some tiny little resistance (Welp, at least they are not as useless as before). The pots that adding DEF or MEDF are helpful as well, probably(Such as suntan lotion,energizer). HP wash optional? Let's make the dream come true.
Im not 100%, but I don't know how much of this can be changed. I vaguely remember Matt or Kevin explaining that the only real thing that can be changed is the amount of def or mdef an item has, but not how it's calculated in damage. Part of the reason why Nexon Nexon'd pages threaten besides the typo, etc. I believe this goes to changing how much 1 def affects damage, as well as any sort of X def = % reduction, etc.