Hello, Below is the sequence of quest events for the hunter's 3rd artifact relic. As you can see below, this quest is a part of the series. This series was completed on a lvl 110 hunter with Highmountain, Stormhelm, zone questing story complete and others at ~50%. Reading through the comments for each quest can provide clarification on some of the prerequisites if you are having trouble getting the quest.
1.1.1 Lending a hand
1.1.2 Rising Troubles
1.2.1 Assassin Entrapment
2.1.1 Urgent Summons
3.1.1 Recruiting Rexxar
3.1.2 Survival Skills
3.1.3 Survive the Night
3.1.4 Champion Rexxar
3.2.1 Calling Hilaire Home
3.2.2 Bite of the Beast
3.2.3 Champion Beastmaster Hilaire
3.2.4 Homecoming
4.1.1 signaling trouble
5.1.1 Unseen protection (5Missions)
5.2.1 Aiding Our Allies (Big Gamy Ribs or highmountain Salmon or silkweave Bandages)
5.3.1 Recruiting more troops
5.4.1 Rating Razik
5.4.2 An offering of Ammo
5.4.3 Note Eating goats
5.4.4 A hunter at heart
5.4.5 Scout it out
5.4.6 Champion Hemet
5.4.7 Champion Addie Fizzlebog
6.1.1 Baron and the huntsmen
6.1.2 Awakening the senses
6.1.3 Champion: Huntsman Blake
7.1.1 Ready to Work
8.1.1 Missing mages
9.1.1 The scent of magic
9.1.2 Assisting the Archmage
9.1.3 knowing our enemy
9.2.1 On the Blink
9.3.1 Feasting the dragon
9.3.2 Cursed to Wither
9.3.3 Hungers End
10.1.1 Leyworm lure
10.1.2 To tame the beast
10.1.3 the nature of the beast
11.1.1 Requesting reinforcements (5Missions)
12.1.1 Informing our allies
13.1.1 Darkheart thicket: Nightmare Oak
13.2.1 The missing vessel (4Missions)
13.3.1 Under the sea
13.4.1 Collecting reagents
14.1.1 Leading by example
14.2.1 Azure Weapon
14.2.2 Meeting in moonclaw
14.2.3 Delicate enchantment
14.2.4 Same day delivery
15.1.1 In defense of Dalaran
After completing In Defense of Dalaran a quest will show up by your artifact altar to empower your weapon with a 3rd relic. Hope this answers people's questions regarding the hunter's campaign for the 3rd relic.
Note: If there are any mistakes, please highlight and comment to help it from causing any grief for future people following this as a event sequence.