Safety Wall...

[Frogboy]

as far as i'm aware there's not really any high end earth elemental mobs that'd be worth having MS or FW for.

most anything you'd want to kill for pvm can be done with either SG or LoV or a combination of both.

examples would be going to nameless and using SG for crowd control as undead cannot be frozen. also you could go to ice dungeon and do mobbing there with LoV and Ice Wall, though i'd imagine it'd be better to be in a party setting with someone who could actually tank a huge mob (HP comes to mind).

basically any enemies you can't freeze can be taken care of by LoV or SG because they're either water elemental and freeze will not affect them, or they're undead and freeze again will not affect them.

it's up to you if you really want safety wall though, otherwise, keep MS for whatever you see fit. it's usually more a matter of playing style as to what skills people use and don't use.