personally, i tried to get every single quartz/gem along the way, with sanguine signet and snowboots. then i switched to winterheart at magma level, using mageflare runes every couple of digs, and if i ran out of stamina, i switched to alchemist's pouch and used my flask. you should probably get the full flask before you attempt nix, though.
and use the reeler hat. i believe it's lucky.
For Nix, Winterheart is only helpful while you still have shield charges. Once those are gone, the -1 Power from Winterheart is basically equal to the +1 Burn damage you'd take without it. So feel free to switch it out once your shield runs out, unless you're really lucky with Sapphire and Diamond spawns to replenish your shield charges.
P.S. I'm totally with you, Reeler hat all the way.
