Cassandra Nova with Mind Gem

Who is the weakest character it would take to defeat Cassandra Nova with the mind gem?

CN has the mind gem and has had 6 months to master it. Other than that she has no specific prep.

1) Mind war only
2) Straight up standard fight.

In a mind war, I'd say possibly Odin and Galactus. Beyond that, the White Phoenix of the Crown.

Ig level or beyond. She would have no limits.

given that base-level cass was able to preform utter mind-phuckery of xavier /w/ his mental prowess amplified to the tenth power *thx cerebra*, i cannot imagine any non-abstract being in marvel or dc beating her if she had the mind gem AND had become proficient in its use.