Conversation so far:
What is the great white owl relating to Cassandra Nova?
On Earth-TRN342, Cassandra Nova has somehow survived for four thousand years and nearly conquered the world as the Great White Owl
who nearly conquered the world as the Great White Owl?
Cassandra Nova nearly conquered the world as the Great White Owl
Was Cassandra Nova the Great white owl?
Cassandra Nova was the Great White Owl
what does Cassandra Nova do while she is the Great white owl?
Cassandra Nova unleashed the Great Corruption and dropped entirely the Veil that separated the Main Reality with the reality of the Revenants, better known as the Mummundrai.
Is Cassandra Nova working with other people as the Great White Owl?
As the Revenants were unleashed on Earth, Cassandra Nova becomes their Queen and soon enough Bishop's presence in this reality came to Cassandra's attention.
did Cassandra Nova take over any other person or animal as the Revenants were unleashed on Earth?
Eventually Cassandra Nova took possession over the body of Ginny and killed another new mutant psychic to begin the Great Corruption.

Question: WHat did she do as their queen?
Self-contained rewrite: What did Cassandra Nova do as the Owl queen?