Niflheim armor took God of War difficulty from “frustrating but doable” when exploring the mists to borderline easy (depending on the creatures/unit types). Three pieces of the passive Health regen armor gets me an additional 1/4 to 1/2 of my life refilled between battles. You can find an axe pommel in Nifl that has a high proc chance of a 6 or 8 second Health burst upon kills (could be runic skill kills, but those happen often enough for me).
My combat rotation for the mist areas is:
4 shots of lightning arrows from Boy,
Flying Swarm Boy runic skill,
4 more shots of lightning arrows (using runic skill refreshes arrow charges),
Glaive Storm runic skill - at this point most of the weaker opponents are dead or very close to dead,
Leviathans Throw on the best target,
Then swing my axe at their weak point until they die
If it’s a hard pack and turns into a long fight, i play more defensive and wait for a Glaive Storm to come back off cooldown.
This strategy let me one shot all of the realm tear encounters in the middle of Nifleheim.
I’m so sad that I’m about to finish all of the side activities (or at least everything that I’m currently aware of). I haven’t gone back and finished Muspelheim (there’s an “Impossible” tier of challenges after you defeat all the standard ones), and I’ve yet to tackle the last Valkyrie fight, but everything else (except the story) is done.
Hopefully they’ve already started the planning and production of the next God of War. This game is easily in my top 3 games of all time. I would say it’s THE best, but I’m aware that I’m still well inside of the honeymoon phase