A while ago I researched the main archmages bios and made a list of everyone who should (and should not) be in Dalaran during the last two chapters of the undead campaign.
Besides Antonidas, canonically the names of three archmages holding the barrier were Conjurus Rex, Landazar and Fordred Aran, while World of Warcraft revealed other two archmage as well helped Antonidas during the siege: Ur and Dalar Dawnweaver.
Ur is a forgotten character in Reforged, but is often mentioned in WoW, because his books on the knowledge of shadow magic and worgen research has influenced so many other important characters and was mentioned in different quests ranging from Silverpine to Elwynn and Redridge mountains. In WoW is stated he died in The Siege of Dalaran.
Also, in The Siege of Dalaran there are 9 unnamed Council Wizards (not to be confused with the Council of Six) and since patch 1.33 in Under the Burning Sky the enemy heroes have all unique names referring mostly to WoW NPCs: Karlain, Ansirem Runeweaver, Ericon, Dalar Dawnweaver, Ulrik von Stromhearth, Pascal Spellbinder and Relios the Relic Keeper
• Archmage Karlain in Dalaran during the scourge attack is inconsistent with his biography, as he was supposedly residing in Goldshire at the time, since he fled Dalaran in peacetime after he he killed one of his apprentices and he was invited back into the Kirin Tor and elected as a member of the Council of Six years later, during Mists of Pandaria time. So I wouldn't include him. Have him there is an oversight imo.
• Ansirem Runeweaver is confirmed in WoW as a member of the Council of Six who fought and survived the third war.
• Ericon is just a random name, he doesn't exist at all in wow or any other official source, I guess it's poetic license by Kam. He can be maintained and killed or get removed altogether.
• Dalar Dawnweaver is a Forsaken in WoW and he confirmed to be a former archmage of the Kirin Tor, he died. But he should die during the siege, not during the counterattack of the last chapter.
• Baron Ulrik von Stromhearth is a noble mage member of the Kirin Tor that survived the third war.
• Pascal Spellbinder, like Ericon is nowhere to be found in WoW, nor do we have any mention of this character in any Blizzard source, so we can assume this character is just a poetic license from the map designer too. He can be maintained and killed or get removed altogether.
• Relios the Relic Keeper is confirmed in WoW as the pupil of Dalar Dawnweaver who survived the war, and we know that his title "the relic keeper" comes by the fact that he stole the ring from the corpse of his dead master. Basically a jackal. Since he is described as a "pupil" of an archmage who was not even a member of the council I wouldn't see him as an enemy archmage, but rather as a minor easter egg of some lesser mage who takes advantage of the disaster to steal stuff or just as a guardian of some treasure box.
Also, we do know that there were also other important Archmages there:
• Archmage Modera, a member of the Council of Six since the second war, fight during the third and survives.
• Archmage Drenden, like Modera he's a member of the Council of Six too, but he dies.
Often mentioned characters such as Bethor Iceshard and Gunther Arcanus confirmed they were killed by the plague, not during the actual siege, so there's no need to see them die violently in war, while other important characters, often demanded by fans like Krasus, Aethas, Rhonin & Vereesa were all away from Dalaran during the attack.
Color legend:
Characters who were present and died
Characters who were present and survived
Characters whose presence is inconsistent with other sources
Characters likely invented by the map maker with no sources at all
It would also be nice to see a differentiation between the specs of the 3 archmages holding the barrier during the siege, to enrich and give more variety to the map: Fordred Aran could be a frost mage, Conjurus Rex arcane-based and Landazar fire.
For the surviving characters I wouldn't mind the same mechanic seen in Reforged for Sylvanas, that when you face her and bring her down to a few hp she vanishes/blinks away.
Sidenote: the 6 members of the Council of Six at the time of the siege had to be Antonidas (the leader), Modera, Drenden and given the task so important for the defense of the city it is assumed the other 3 archmages who held the barriers: Fordred Aran, Conjurus Rex and Landazar. (Kael'thas had given up his position shortly before the siege. Ansirem Runeweaver joined the Council of Six during the Third War, and is known for sure to have been a member of the Council when Garithos liberated the city and condemned the blood elves. So we can assume that he assumed the role right after the murder of the previously mentioned council members.)