It's a setting in Magic: the Gathering.
There are three main features of Arcavios (as far as Strixhaven is concerned).
A snarl is a tangled knot in the weave of magic
A star arch is a floating archway of stone, smooth inner curve, and a jagged outer curve of spires resembling the rays of a star
When two worlds collided and created Arcavios, the five ancient dragons were hatched from that magical energy
The Oracle of Strixhaven is the wisest, most powerful mage in Arcavios.
When the Oracle dies, their consciousness is thrown back to the dawn of time and becomes a new Archaic, a gargantuan celestial who speaks in riddles to avoid time paradoxes.