One of my D&D players is a wizard from Neverwinter. He found notes about the "Covenant" and thought to me that he wants to find any member. Can you tell me - is there any pieces of information about the structure, members or the base? I found information that Covenant has a reborn and move to the Waterdeep.
Here's everything I know...note that all of this comes from older edition lore. There is no mention whatsoever of The Covenant in 5th Edition. Information about this organization only appears in 2 books, both of which are from 3.5E. Grand History of the Realms and City of Splendors, Waterdeep.
The mages Aganazzar, Ilyykur, Presper, and Grimwald found the School of Wizardry in Neverwinter and begin taking on apprentices from around Faerûn.
-Grand History of the Realms, p88
An alliance of mages called the Covenant is founded to promote peace among the human kingdoms of the North and prepare them for future conflicts with the orcs. The architects of the organization are Ilyykur, Aganazzar, Presper, and Grimwald, hereafter known as the Four Founders.
-Grand History of the Realms, p96
From these two quotes, we can see who founded the organization originally. And frankly, we don't know a lot about them. Some of them have spells created by them--the only one of which that still exists in 5E is Agnazzar's Scorcher.
Methods and Successes
Again, we have very limited information here...but The Covenant seems to have no issue getting others to do their dirty work for them.
The mages of the Covenant begin to secretly manipulate and influence the Uthgardt tribes of the North through their Art. By season’s end, the tribes stand united against the goblinkind of the Savage Frontier.
-Grand History of the Realms, p97
Put more simply, The Covenant used magic to manipulate the nomadic tribes of the Sword Coast into forming an alliance against Goblins and Orcs. This leads to...
At the whispered request of the Covenant, the Uthgardt begin hunting down and slaying orc chieftains, killing a score of them over the next five years. Their action prevents the formation of another orc horde.
-Grand History of the Realms p99
Mirabar is overrun and plundered by goblin hordes that stream south out of the Valley of Khedrun. Their numbers are thinned by the savage ferocity of the Uthgardt tribes who battle them day and night for the better part of a season before the goblins are eventually annihilated by the Covenant-whelmed humans of the Dessarin Valley.
So, The Covenant "built" an alliance of Uthgart tribes, then used them as a weapon against the orcs and goblins. Then magically buffed the humans of the Dessarin valley to ultimately stop the invasion.
Up to this point, things have been going pretty well for them. It's not to last...
The Uthgardt alliance defeats an ogre-led army of orcs and goblins that emerges from the Evermoors. The warriors of the Elk tribe fall almost to a man in the defense of Flintrock. On the verge of extinction, these once-proud people become little better than bandits.
The Uthgardt Alliance, backed by the hidden hand of the Covenant, fades away as the tribes begin to feel the loss of their warriors.
From there, history is silent about The Covenant for nearly 200 years. When next we hear about them, they basically get trolled by the Red Wizards of Thay.
The mages of the Covenant gather a great, armed host from the human settlements of the North to confront an orc horde massing in the Spine of the World. In a move known as the Orcgates Affair, the Red Wizards of Thay magically transport the horde far to the south by means of great portals. The North is spared much devastation, and the failure of the orcs to appear deals a significant blow to the influence and prestige of the Covenant.
The Covenant ultimately determines that the Red Wizards were responsible for the above, and starts a quiet crusade against them. It doesn't go well.
- Ilyykur, one of the founders, dies in a spellbattle with an archlich (and former Covenant member) in 1063 DR
- Red Wizards kill Agnazzar when they assault the School of Wizardry in Neverwinter in 1081 DR
- Presper and Grimwald flee Faerun and the rest of The Covenant goes underground in 1101 DR.
In the year 1372 DR, a wizard named Savengriff (an apprentice of Khelben "Blackstaff" and a Harper) joined up with Prespur and Grimwald to refound The Covenant.
In the Year of Wild Magic (1372 DR), Savengriff returned to Waterdeep and took a room at the Inn of the Dripping Dagger (T3). Although he still maintains his ties with Those Who Harp (and the Tel Teukiira as well), he now has a new loyalty. During his travels Savengriff located the long-absent and legendary Prespur and Grimwald. After lengthy discussions, the three agreed to reinvigorate the ancient cabal of good-aligned mages known as the Covenant. Savengriff is the fi rst to return to Faerûn, and he is actively seeking like-minded mages of power to join this ancient brotherhood.
-City of Splendors, Waterdeep, p31-32
And...that's it. That is all we know about the Covenant as it exists today. One of the Blackstaff's apprentices tried to restart it in 1372 DR, 115 years before the start of D&D 5th Edition (1487 DR, the end of the Second Sundering) and we have heard absolutely nothing about them since.
What we can determine
Based on this information, we can make a few assumptions about The Covenant
They are an Alliance, not a structured organization: The Covenant is always spoke of as an alliance, which would be a collection of 'equals' working towards a similar goal. There may be leaders among them--particularly the founders, who would push the alliance forward--but it's very unlikely that they are as structured as, say, The Harpers. It is, essentially, a bunch of mages who agreed to work together on a particular thing, which is...
The goal of the alliance is to defend against Orcs and Goblinoids: Pretty much everything they did, until the Red Wizards picked a fight with them, was focused on this. Given that this was the stated goal of the alliance, this is unsurprising.
As for the rest...well, that's up to you as the DM. Has the Covenant regrown into a significant alliance? Have they been successful in keeping the Orc and Goblinoid tribes suppressed? Did Prespur and Grimwald come back? Did the alliance fail to get traction and has it been floundering for the past century? Have they been trying to rebuild the Uthgart into an alliance? Is the reason we haven't heard about them because they've been staying much, much quieter to avoid notice by the Red Wizards?
Ultimately, we don't know a lot about this organization. But that's okay...that means that you, the DM, can make stuff up and fill things in as it serves the plot.