WotC have confirmed this is the "full" Tiamat.
Why is that actually? I mean, none of the D&D lore, no matter the edition supports it, and yet you always make Tiamat one of the most powerful - if not the most powerful - of your designs. So just wondering.
(And I've said before - I way prefer her as the Ur-dragon, instead of a goddess.)
Because Tiamat is the Mother of Monsters, the spawner of Primordials, the goddess of the cosmic sea from whence all things come, she is the terrible, the beautiful..
Wikipedia said:She is the symbol of the chaos of primordial creation. She is referred to as a woman,[4] and described as the glistening one.[5] It is suggested that there are two parts to the Tiamat mythos, the first in which Tiamat is a creator goddess, through a sacred marriage between salt and fresh water, peacefully creating the cosmos through successive generations. In the second Chaoskampf Tiamat is considered the monstrous embodiment of primordial chaos.[6] Some sources identify her with images of a sea serpent or dragon.[7]