It can only target one party member at a time, so a easy "brute force" solution is auto-revive (white magic has "reraise" which you can cast on dedicated tank or healer). You can also try to avoid red chests and pots until you feel more confident.
Yeah, I get that since it's not loss you can revive, but the way I like to play is to not get killed (or preferably hurt) at all and getting my dudes killed annoys me :d
Or grind until you are level 9999 with full job and race for 200h...
In this game, since 3.02 and the introduction of ruler"s rules, if you have difficulty it's because you want difficulty.
Setting enemies stats to 1 isn't exactly decreasing difficulty (it's throwing combat and progression system out of the window altogether).
Also I didn't see anywhere in the damage formula for that skill mention of enemy stats, so I think even with all stats 1 they'd still one-shot my guys.
In fact it's even more ridiculous than having these skills of unavoidable insta-death (I'm more okay with normal insta-death btw since you can raise your death\ascension resists via in-game means - and I'm not aware of equivalent for resisting tons of "untyped damage")
Also the troublesome part of this skill is that it gets stronger the more "death number" u get, so in case it's "number of foes defeated overall" it can be tricky to get your health scale faster (since it's not like you get 100 hp for every enemy you kill, unless you get billion hp later on in which case you can disregard this argument)
Ah, yes - that skill seems to have at least +1000 speed as mimic acts before Gadabout's Lucky song, that has +800 speed