Warmth Potion

The Frost Moon is the reason this potion exists. Nearly everything that spawns during it sits on the affected list, and one bottle covers the event from the first wave to sunrise without a top up. The Frost Legion is the same story on a smaller scale. Outside those two and Deerclops, you will go whole playthroughs without wanting it.

Against Deerclops the reduction only applies to about half of what it throws at you. The hands that rise out of the ground land at full strength, so do not treat the potion as permission to stand in them. There is one plain oversight too: the zombie variant that spawns in the snow reads as a cold enemy and gets no reduction at all.

The name misleads people into drinking it for the Chilled and Frozen debuffs. It does nothing for either. That job belongs to the Hand Warmer and the accessories built from it, and the two are worth running together for a snow trip.

The reduction is ordinary damage reduction, so it piles onto an Endurance Potion and onto whatever your armor and accessories already give you. On a defensive summoner build going into the Frost Moon, the combined total is enough to change which waves you can stand still for.