Make sure Captain Marvel is the only cost 5 you have, so it will have a big chance that it will be played when drawed, and can combine well with Maw at the end of the game.
An early Cosmo, Ebony Maw or Cloak won't hurt you much, especially cause they have decent power, and while Ebony Maw restricts Agatha's missplays, Cloak can maker her fix it. Cosmo is excelent because restricts your opponent from revealing in a loc you will most likely be able to contest with your powerhouses (that wont be hit by Shang Chi), while having another win condition that is Dracula: the deck power Breakdown is 6.8, so the chances you are playing a 4/7 card is actually very high, also with the bonus it can be destroyed by Shang or Enchantress.
If Agatha throw Wave turn 3, your chances to win the game gets exponentially high. Wave Turn 4 still not bad at all. And if it's turn 5 Wave you can maybe stop Sera and Bounce decks.