An inaccessible mountain to the North.

This encounter can occur anywhere along the base of Mount Baratok.

North of the mountain lake, the trees begin their steady climb up the slopes of Mount Baratok, its monolithic presence oppressive at this distance. The ground here is rocky, uneven, and tiring to navigate. Even the wolves avoid this neck of the woods. Soon, you climb above the blanket of fog that engulfs the valley. Dark thunderclouds roll overhead.
You see an elk standing on a rocky spur about sixty feet away. Suddenly, it assumes the form of a man in tattered black robes. His hair and beard are long, black, and streaked with gray, and his eyes crackle with eldritch power.

The Mad Mage of Mount Baratok (CN male human archmage) came to Barovia more than a year ago to free its people from Strahd's tyranny, but he underestimated Strahd's hold over the land and the creatures in it. After a battle between the two in Castle Ravenloft, Strahd drove the Mad Mage to the mountains and sent the wizard hurling over Tser Falls (area H). The wizard, his staff and spellbook lost, survived the fall and retreated into the mountains, hoping to regain his power, only to be driven mad by the realization that he no longer has any hope of defeating Strahd or freeing the people of the vampire's damned realm.

The Mad Mage has forgotten his name and the world whence he came. In fact, he doesn't remember anything that happened before the madness. He suffers from the that their evil agents are everywhere and watching him. Believing that the characters aim to kill him, the Mad Mage unleashes his destructive magic. As he tears into them, he shouts, "You think my magic has grown weak? Think again!" If he is reduced to 50 hit points or fewer, he shouts, "Tell your dark masters they can break my body, but never my spirit!" He then tries to escape.

Under normal circumstances, a greater restoration spell cast on the Mad Mage would restore his wits and ends the madness, allowing him to remember that he is none other than Mordenkainen, an archmage of Oerth and the leader of a powerful group of adventurers called the Circle of Eight But in this case, the Mad Mage has cast a mind blank spell on himself. As long as that spell
remains in effect, his sanity can't be restored by any spell. If the characters surmise that powerful magic is preventing them from restoring the Mad Mage's wits, they can, with a successful DC 15 Charisma (Persuasion) check, convince the Mad Mage to divulge the reason why their spell failed. A character can also ascertain the cause of the spell's failure with a successful DC 18 Intelligence (Arcana) check. The Mad Mage's mind blank spell has a remaining duration of 3d6 hours, after which his madness can be cured normally.

The Mad Mage has a different spell list from that of the archmage in the Monster Manual, and he has already used one 1st-level spell slot to cast mage armor on himself, one 4th-level spell slot to cast polymorph on himself, one 7th-level spell slot to cast Mordenkainen's magnificent mansion (see "The Mad Mage's Mansion"), and one 8th-level spell slot to cast mind blank on himself.

Cantrips (at will): fire bolt, light, mage hand, prestidigitation, shocking grasp
1st level (4 slots): detect magic, mage armor, magic missile, shield
2nd level (3 slots): mirror image, misty step, web
3rd level (3 slots): counterspell, fly, lightning bolt
4th level (3 slots): Mordenkainen's faithful hound, polymorph, stoneskin
5th level (3 slots): Bigby's hand, cone of cold, scrying
6th level (1 slot): true seeing
7th level (1 slot): Mordenkainen's magnificent mansion
8th level (1 slot): mind blank
9th level (1 slot): time stop

THE MAD MAGE'S MANSION

If the characters rescue the archmage from his madness, he invites them to his "mansion." He leads them up the mountain to an invisible doorway that serves as the entrance to his extradimensional lair, created using the Mordenkainen's magnificent mansion spell. There, he provides them with food and sanctuary away from the prying eyes of Strahd and his spies. Characters are free to take a short or long rest, during which time they aren't disturbed.
Mordenkainen is familiar with worlds beyond his own. For example, if the characters come from the Forgotten Realms and mention this fact to Mordenkainen, he asks them if they know his old friend Elminster of Shadowdale.
If Mordenkainen isn't the party's ally as foretold in Madam Eva's card reading (see chapter 1), he declines to join them if asked. With his wits restored, he sets out to find his missing staff and spellbook, leaving the characters on their own. He doesn't allow them to help him, for he fears they might be tempted to steal either his staff or his spellbook. (Being an adventurer himself, he knows how the lure of powerful magic can bring out the worst in adventurers.) Before he leaves, as a parting gift, the archmage imbues each character with a charm of heroism
(see "Supernatural Gifts" in chapter 7 of the Dungeon Master's Guide).

FORTUNES OF RAVENLOFT

If your card reading reveals that the Mad Mage is the party's ally in the battle against Strahd, Mordenkainen can be persuaded to help them once his sanity is restored. He won't join them on their travels, but he will help them in a fight with Strahd if they have discovered where to find the vampire and how to destroy him. With his sanity restored, Mordenkainen can be stubborn and difficult even with his friends, and doesn't suffer fools. He normally spends more time listening than talking, but when he does speak, his pronouncements are authoritative and not to be questioned. The archmage has never had his fortune read by Madam Eva and doesn't care to, but if he is told about the Holy Symbol of Ravenkind, the Tome of Strahd, and the Sunsword, he insists that these items be recovered before he and the party confront Strahd. If Strahd is defeated and Mordenkainen survives, the archmage gladly accompanies the characters back to their world if they
invite him, if only not to disappoint them.