Heart of Winter expands Icewind Dale with a major new quest. A powerful barbarian leader has returned, and is gathering the tribes to wage a devastating war on the Ten-Towns. The party is asked by a suspicious shaman to try and stop the war from happening.
The new quest is designed for at least 8th level characters, it can be entered while playing Icewind Dale, or players can import their party in a Heart of Winter only adventure, or create a new one, starting with 8th level characters.
The game adds over a hundred new items, dozens of new spells, new powerful creatures, increases the level cap of the game to over 20 and adds user interface improvements from Baldur's Gate 2. Like Icewind Dale, gameplay focuses on battles and tactics, with more emphasis on spellcasting due to the higher-level characters and monsters.