She's the perfect example of a card that is an enabler and a payoff in one: she's a better Corrosive Mentor as a 4/4 with menace and she turns into a card advantage engine when creatures die from wither, sweepers like Darkness Descends, blight from Lorwyn Eclipsed , Toxrill, the Corrosive, and all the payoffs like Nest of Scarabs that she's backwards-compatible with
While Counterspell is the most well-known, Id recommend Arcane Denial as the must-include counter
Im looking at you, ST10 Trafalgar Law
More details will be available closer to the set's release
This attracts the attention of canny investigators like the famous Alquist Proft (who may as well be a cockier, more genial Sherlock Holmes)
You can get this card from opening Charizard Booster Packs