Originally Posted by
GotSomeQuestions
As mentioned Coyle (Escort the Expedition and Hold for Reinforcements, almost entire the latter), and Acute Delirium are the most challenging of the protection quests (although The Bookbinder Rescue can be tough for certain builds). You meant Redemption, not Stopping the Sahuagin. And Sirgog brought up Waterworks already. Here are some others, in roughly ascending order by quest level:
Stand Your Ground (Sharn Syndicate), The Bookbinder Rescue (Sharn Syndicate), A Small Problem (Phiarlan Carnival), Guard Duty (Three-Barrel Cove), Gladewatch Outpost Defense (Marketplace), The Rescue (Threnal West 2), The Last Stand (Red Fens), Let Sleeping Dust Lie (Vale of Twilight, protect the Queen), Dream Conspiracy (Inspired Quarter), The Shipwrecked Spy (Inspired Quarter), and Wrath of the Flame (Amrath) all have "friendly" NPCs that you must protect.
Faithful Departed (House Phiarlan), Slavers of the Shrieking Mines (Restless Isles), Let Sleeping Dust Lie (Vale of Twilight, don't kill the other spiders), and Prey on the Hunter (Reaver's Refuge) have "unfriendly" NPCs that must survive.
The Cannith Crystal (Korthos), Protect Baudry's Interests (Harbor), Desert Caravan (House Phiarlan/Zawabi's Refuge), From Beyond the Grave (Delera's Graveyard), Finding the Path (Inspired Quarter) and the Mabar Summoning Chamber (Mabar event) all have objects that you must protect.
I think that's everything, but I might have missed one or two.