Aiding Askr - PoStorms (Alternative BoT Access)
In order to even accept this quest you'll first need to have completed one trial in the Plane of Justice as well as find one Storm Giant Head, a fairly common drop from many different enemies in Plane of Storms and bring it to Askr. Upon completing these two things Askr will talk to you and allow you to begin this quest.
Hail, Askr the Lost
Follow Askr's dialogue and he'll give you Askr's Bag of Verity. You'll need to collect three different items to place into this bag and combine them. The items you need are Storm Volaas Beard (Southern Ocean Giants), Storm Taarid Bone (Western Desert Giants), Storm Satuur Sash (Eastern Forest Giants).
All three of these locations are marked on the map below. In addition each of these three locations has a small raid boss enemy which you'll also need to kill for the next part of the quest to collect Esoteric Medallions. You only need two of the three medallions that drop - I'd recommend you collect them as you do the first part to save time.
Storm Satuur Sash - Eastern Forest Giants (an irmin fannsk, an irmin her megir)
Storm Volaas Beard - Southern Ocean Giants (a hleyta menn, a hleytis maor, an her megir)
Storm Taarid Bone - Western Desert Giants (a jotna fannsk, a jotna her megir)
Once you've completed the first part of the quest and combined the three items above in the Bag of Verify to create a Sealed Bag of Verify which you'll then want to return to Askr the Lost. Hand it to him and then complete the little bit of dialogue below in order to get a second Bag of Verify.
Hail Askr the Lost
/say What Bastion of Thunder
With this Bag of Verify you'll want to place two Esoteric Medallions inside before hitting combine. The two Esoteric Medallions can be found in any of the three giant camps marked on my map above. A successful combine will create an Esoteric Meld which you'll then want to hand to Askr the Lost to complete the quest. This step rewards you with the final character flag from this quest.
That's all there is to it! The final step of this quest would require you to zone into The Bastion of Thunder via the ZL in Plane of Storms. Doing this will add the Talisman of Thunderous Foyer to your Keyring. Note: For me I didn't have to zone into BoT in order to get the Talisman added to my keyring, it was added after talking turning in the Esoteric Meld to Askr.