Spider-Gwen, as she is affectionately called, is a fantastic new Hero to add to the stable. She shares the same stat line as Spider-Man and Groot, which may inspire you to put her into Protection with such a strong DEF stat.
Her effectiveness is derived from two factors: She is a Web-Warrior and she has an exceptionally powerful Hero ability.
"Free" readies are rare in this game outside of Quicksilver, and building for Gwen is a delcious puzzle. Here is a breakdown of Response/Interrupt Cards that are available to trigger her Ready:
(Responses) "You'll Pay For That!", Chase Them Down, Moment of Triumph, Surpise Attack (Interrupts) Skilled Strike, Mean Swing, The Best Defense
(Responses) Brains Over Brawn, Lay Down the Law, Turn the Tide (Interrupts) Foiled!, Great Responsibility, Making an Entrance
(Responses) Moxie (Interrupts) Last Stand, Teamwork
(Responses) Counter-Punch, True Grit (Interrupts) Defiance, Deflection, Desperate Defense, Expert Defense, First Hit (if using the second ability), Get Behind Me!, Leading Blow, Never Back Down, Pre-emptive Strike, Side Step, Stand Together, Subdue
(Interrupts) Emergency, Warning (Even these old cards can see use!)
Protection has a ton of ways to allow Gwen to avoid damage and ready during the Villain phase. Aggression tends to provde cards that Ready Gwen during the Player Phase, with a nice spread of dealing damage, removing threat, and healing.. Justice has a decent number of cards, but you may find it tough to trigger the Events. Leadership is the most limited, only having a few specific-use cards.
Gwen herself includes 9 cards that can ready her in both the Player and Villain phases, so the consideration of how many additional Response/Interrupt cards may not be a prime consideration, but I wanted to list them for your consideration.
Givern Gwen's fairly consistent ability to Ready, she benefits strongly from boosts to her Basic powers.