Icecrown 80 - 80
When you enter the zone head to the Argent Vanguard(1). Accept the quest from Highlord Tirion Fordring and refresh it at Crusader Commander Entari. Grab all of the quests that pop up in town then head out of town to the west and kill 15 Forgotten Depths Nerubians, collect 10 Forgoten Depths Venom Sacs and free 8 Webbed Crusaders. When you're done all 3 of these quests return to town and turn in all of your quests. After you turn in all 3 head to Crusader Commander Entari and grab the quest he has.
Head over to Penumbrius, he's at the southern portion of town. Refresh your quest at him then mount a Argent Skytalon and fly it north to Scourgeholme(2). Here you have to find a Captured Crusader and use the first ability on your action bar to pick him up. Once you've got a hold of him fly back to town and Use ability number two on your action bar where all the tents are in town. (Using it at where you mounted the dragon will not work.) Do this two more times then refresh your quest.
Head over to Siegemaster Fezzik and refresh your quest. What you have to do now is fly up to one of the cannons surrounding town and blast off 100 Scourge Faces and 3 Frostbrood Destroyer faces. When you're done with the face blasting return to Fezzik and turn in your quest. Grab the new quest that pops up in town then head out to (3). Turn in your quest here and grab all of the new quests then fly back to Scourgeholme and this time do;
"The Purging of Scourgeholme"
Kill 3 Forgotten Depths High Priests
Kill 3 Forgotten Depths Underkings
Kill 8 Reanimated Crusaders
"The Scourgestone"
Collect 15 Scourgestones
"The Restless Dead"
Use your holy water on 10 Reanimated Crusader bodies
After you complete all this fly south to Crystalsong and enter the Undying Thicket (It's the large purple section of Crystalsong. Here you need to collect 10 Crystalline Heartwood off the ground, 10 Ancient Elven Masonry from in and around the ruins and 8 Crystallized Energy which drops off the mobs here. When you have everything return to the Valley of Echoes town in Icecrown. Turn in all of your quests and ignore the rest of Icecrown for the time being. It's to far spread out and not worth it. If you're still not level 80, fly east to Storm Peaks.