A lot of these cards are standard in Agatha lists as of right now, so I would say my innovations (post Zabu/Surfer nerfs + meta changes) were the following:
Sunspot + She-Hulk - With Chavez and Agatha Harkness in our deck, the odds that we have Sunspot by turn 1 or 2 are 40% and 50% respectively. He does have the potential to backfire on us, if drawn on Turn 3 (20% chance, if still in deck) and Agatha decides to play him instead of Wave or Sif--completely ruining our game plan in the process. However, I think the odds of that happening (I estimate between 4% to 5%) are worth the huge benefit of having him and She-Hulk around.
In case you were worried, She-Hulk is also never discarded by Lady Sif, because we have no way to spend 2 energy on turn 2--therefore she will always cost 4 or 5 on turn 3.
This combination wasn't as viable back when Spider-Man was everywhere, but now that Zabu has been nerfed; it's awesome to determine where your power goes on Turn 6 with She-Hulk. The nerf to Silver Surfer also reduces the amount of Killmongers that will counter our Sunspot.
Jessica Jones (alternatives = Typhoid Mary, Crossbones, and White Queen) gives the deck a much needed 4-cost that can be played proactively on Turn 4--for when we play Lady Sif on 3, but don't have Ghost Rider. It felt bad needing to play Shang-Chi, Enchantress, or Typhoid Mary on 4, so hopefully we'll have either Ghost Rider or Jessica around.
Why these cards were improvements:
With the removal of Typhoid Mary and Red Skull, instead of playing awkward cards on curve and showing where our power is + being weak to Shang-Chi, we instead have the option of passing Turn 5 (Sunspot +5 power) -> She-hulk + Taskmaster (can be 14 power when played first if you went Wave -> Agatha,) Shang-Chi, Enchantress, or Ghost Rider.
We still have Sera as an option on Turn 5, allowing us to play two of our powerful 4-cost cards on turn 6. Not as optimal as passing with Sunspot around + She-hulk in hand, but this gives us a back up plan--especially if we didn't get to play Ghost Rider on 4, after Lady Sif.
Overall, I think this deck is good enough to hit infinite, but you'll need to have great cube management and put a lot of time in compared to other lists. Playing Agatha is fun, though!