The Lich can either be really scary or go down like a punk. He's basically set up to blast you through the walls, but much like Shades, this opens him up to getting an arrow in the face. Skirmishers might actually have the most trouble here, as Guardians can tank the damage with careful use of Guard, Hunters have Sniper Shot, Mages have their own long range options that can also slap status on him, and Clerics? Clerics have a few options that just straight up ruin his day.
Elemental attacks are mostly Mage's domain. You could also give a Cleric a piece of late-game equipment, but said equipment isn't even available for the Tundra.
That said, the enemies on the Tundra can be rough, and are certainly more than their resistances. Defenses are well worth taking if you can get them, because the enemies are much more effective at ganging up on you here.