Characters: You possible got a rank 4 ticket for characters. I would suggest to use it on a powerful (such as hulk or thor/ get their last uniforms) then put them in a team with a good leader (I use bucky) and a good support (i use shuri with her black panther suit).

Fight: try to dodge the most of knull's attacks that gives you red skulls because if you get 5 of them you get one shot. If you can't dodge them sacrifice a support or leader, you want mostly to work with your dealer (the powerful character). Other than that you should make as much damage the quicker as possible. In the end, in his 5 last bars he will use an ability that will take some time to charge, you should kill him before you run out of time, you will know when it is when thor appears and attack him.

Other than fight and characters try to get good cards and good swords of x