an addendum to my previous Ludinus Da'leth is Athodan from Aeor theory!
Athodan may have been consecuted.
the relic Athodan found was a Luxon beacon, and upon "weaving of necromantic glyph work [Athodan] revealed unique arcane properties" of the beacon. this may have been the ritual of consecution.
if this is the case, Athodan could have been killed in the crash of Aeor caused by the gods but was later reborn
the same elf that would survive the fall of Molaesmyr and go on to join a cabal of mages called the Cerberus Assembly, the same name as a cabal of mages from the Age of Arcanum in the Dwendalian Empire
as long as there was a beacon—any beacon—within 100 miles of Molaesmyr during Ludinus's birth, this is entirely possible.
we know Aeor had a beacon and that the elves of Molaesmyr were studying Aeorian artifacts. there is a possibility one of the artifacts brought back to Molaesmyr was a beacon (if there wasn't one already present within the necessary radius).
Ludinus was said to have been one of the mages studying Aeorian artifacts in Molaesmyr before its destruction.
was his interest due, in part, to the memories recovered during his anamnesis as a younger elf? was he compelled to join the Cerberus Assembly because of its shared name with the mage group from the Age of Arcanum?
if Athodan was killed in the crash of Aeor, they would have died close to the beacon they were studying. if Athodan survived the crash, there is a chance their study of the beacon yielded an elongated lifespan that allowed them to simply weather the Calamity before dying near the Aeorian beacon.
this latter possibility is only necessary to ponder due to the potential rate of reincarnation facilitated by the presence of Luxon beacons. there are supposedly thousands of souls inside the beacons, and who knows how quickly those souls reappear in humanoids born within range.
there is also the possibility Athodan was in a stasis bubble like the ones encountered by the Mighty Nein, and the elves of Molaesmyr dispelled it. that killed Athodan, but due to their consecution, their soul was pulled into the beacon, which was then transported to Molaesmyr, where Ludinus was later born.
Ludinus being a reincarnated Athodan also explains why he was able to manipulate the abilities of the beacon in the malleus key in the Hellcatch to bring the solstice to them. Athodan had intimate knowledge of the workings of the Luxon beacons, and therefore, Ludinus knows how to influence some amount of control over the temporal capabilities of the beacons.
so, in summary: my theory is Athodan from Aeor—the head of the Factorum Malleus "Creator Hammer" project, a plan to use machines called malleus keys to free Predathos, the god eater, who is sealed in the moon Ruidus—was consecuted during the research into rejuvenation done with/on "the relic" AKA a Luxon beacon and therefore reborn as an elf of Molaesmyr named Ludinus Da'leth