4h until new cycle and cant decide.
Was playing around a bit on eternal and frozen orb sorc seemed to stack FB quite quickly.
Glacier also appears to have some passives for cold dot.
Haven’t played rogue yet and I noticed in my stash I have a frostbite quiver for Puncture?
Detonating Arrow has a cold convert passive though, so if the skill visually looks cool I’d be into that; but the above quiver seems great for Puncture frostbite.
Say hello to Cecil. Frostbite sorcerer, who could probably be runemaster just as well. Uses lightning blast or frost claw, sometimes even cold nova when he’s bored. Ice barrage for some bosses for extra punch and to run out of the danger. Runemaster version would drop nova for runic invocation for buffs.
https://www.lastepochtools.com/profile/apohawk/character/Cecil
No idea how it will work in season 2.
Snowdrift is kind of mandatory for this build to convert freeze rate multiplier into frostbite penetration. Use 4 grand idols with frostbite duration. Frostbite shackles are nice to have. Celestial rainment and elder eye’s implicits beat any unique i could think of. Add some chance to shred armor, which runemaster’s passive converts to chance to apply frostbite.
Well, it’s all there in the profile. There is still some room for improvements for Cecil, but we all have our flaws 
Side note, my characters rarely reach 300C, so manage your expectations accordingly.