Ironheart

Riri Williams, expelled from MIT, builds armour with stolen resources and falls in with Parker Robbins / the Hood, whose cloak grants magic at a cost.

The finale reveals the cloak's source: Mephisto, played by Sacha Baron Cohen — a demon lord who has now entered the MCU. Riri strikes a deal with him to resurrect her dead best friend.

This is a seed for something after Doomsday, not for Doomsday itself. Optional.