Act 5 Quest 3: Prison of Ice - Diablo 2
Quest Location: Frozen River
Quest NPC: Malah & Anya
Quest Goal: Rescue Anya
Reward: Scroll of Resistance (+10 Resist Permanently) & 1 Rare Class Specific Item
Flag: Portal to Hall of Pain is opened
Speak with Malah in Harrogath to begin this quest or find Anya in the Frozen River zone and speak with her. For this quest all you have to do is locate Anya in the Frozen River then return to Harrogath to speak with Malah and retrieve a special Thawing Potion that you'll use on Anya. You'll find the Frozen River entrance in the Crystalline Passage.
Once Anya has been freed return to Harrogath and speak with both Malah and Anya for rewards. Malah will give you a scroll that adds +10% to all of your resistances and Anya will give you a rare class specific item. With Nihlathak now no longer in town you'll want to speak with Anya to Gamble from now on.
Last but not least, Anya will open a portal for you that leads to the next quest, Act V Quest 4: Betrayal of Harrogath and also to one of the most famous Diablo 2 farms, Pindleskin. If you're playing on Hell difficulty and you plan to farm Pindleskin it is strongly recommended you do not get the Waypoint in Hall of Pain as it'll close this portal.