From https://www.reddit.com/user/kookoobah/
CARD NOTES
Nova - better on Turn 6, play earlier if you don't draw Sera.
Angela - reserve for Turn 6 for surprise power, but is fine earlier. Helps vs Leader.
Armor - counter Hood, Nova, Bucky Barnes, Arnim Zola. Can be a flex slot.
Scarlet Witch - Dream Dimension, Kamar-Taj, Death's Domain, Space Throne, etc. Any location that prevents you from playing cards.
Sentinel - play as many as you can.
Mysterio - play after Bishop, Turn 6 surprise with Nova.
Lizard - play on lanes where they have a 1-drop or a 9-power card, then use Killmonger or Shang-chi to open it up.
Bishop - play as early as you can
Killmonger - combo with Nova, help Lizard
Shang-chi - play on Turn 6 for 8 cubes, help Lizard
Enchantress - play on Turn 6 for 8 cubes, turn off Wong as early as you can
Sera - play on Turn 5. If not, retreat unless you have a good read.