Eldwurms

The Eldwurms (also known as eldwyrms, elderwurms, grand dragons) are old, wise, and powerful dragons in Dota 2's lore.

The Eldwurms' Roost
Auroth often mentions a place where the Eldwurms congregate to roost. This roost is a vantage point, since Auroth was able to see the Ancients' battlefield from this roost.

Description
The Eldwurms are defined by their age and knowledge rather than their common physical characteristics since it seems that any species of Dragon can be an Eldwurm if they fulfill the requirements of being old and wise. Hence, they are an intellectual class of dragons rather than a species or strain of dragon.

The Eldwurm Eddas
Written by not just one Eldwurm but any of them, the somewhat open-ended Eldwurm Eddas (a.k.a. Eldwurm's Edda, Eldwurms' sagas, etc.) is a massive poem, like an edda or saga, that recounts the colorful history of the Eldwurms, as well as any other wonders and terrors of the world that its authors might record.

The Elder Myth
The Elder Myth is, well, an ancient myth. Not much is said about its contents. It has something to do with Auroth for some reason. The only thing currently known about the Elder Myth is that if one will petition two dragons for their thoughts on it, it may result in receiving five replies.

Resisting Death
In their search for knowledge, ancient eldwurms have learned techniques for staving off death itself.

Notable Eldwurms
It would seem that most of the Eldwurms are dead, according to most of the responses that mention them.

Heroes
Slyrak is a massive and powerful Eldwurm who possesses many centuries of wisdom. He is best known for transferring his strength and wisdom to this, the latter of which has been merged with Sir Davion's valor alongside the other Eldwurms' wisdom, both of which are now the source of his nobility. Auroth the is yet another Eldwurm, but she is actually the last Eldwurm left, not counting Slyrak who partially exists in this world. As such, she's the last keeper of the Eldwurm's Edda and perhaps the oldest Eldwurm in existence.
 * Davion (and maybe Slyrak) wishes to those that he has slain to be ushered to their final resting place by the Eldwurms.
 * A somewhat similar fate shall happen to him when he dies, as he joins the Eldwurms in death, implying that these sage dragons have already crossed the veil long ago.
 * During battle, Davion (and maybe Slyrak) will invoke or swear upon the "honor of the ancients". It's uncertain if these "ancients" refer to the Eldwurms or something else.
 * She claims to be a "Maidenwurm" before she became an Eldwurm, further proving that the Eldwurms aren't a race or species of dragons, but rather a status that can be achieved by dragons, akin to a draconic version of a druid, sage, or philosopher.

Characters
It's implied that Vyxia is an eldwyrm because of her "grand dragon" title, a title that was also used to refer to another dragon of large proportions who's implied to be Slyrak himself, judging by the evidence. Seeing how all that remains of Vyxia is a sword in Sir Davion's possession that's made from her scales, teeth, and fiery blood, she is most likely dead.

Enemies
It seems that the is ill-disposed to the two remaining Eldwurms. He seeks to battle and perhaps kill Slyrak and he has done something wrong to Auroth that has shocked the Netherdrake, implying some sort of backstabbery. His wrongdoing against Auroth may have taken place after he warmed up to her in Artifact.