Stephen and the Avengers are fighting Thanos, Tony's daughter and Stephen's wife, Jax is also helping. Jax is the black witch, like how Wanda is the scarlet witch.

Stephen and Jax both know she has to do the snap, instead of Tony. But no one else knows, just so they don't have to try and think of a way to get Jax out.

The team, Jax and Stephen are all standing in front of Thanos. Jax and Stephen are together, the others next to them.