Somebody close to Stark, in a idea world I would loved it to be either Pepper or Morgan (off Screen obviously for Morgan) but Happy and/or Rhodey can work as well.

Probably a character we all love then they will undo it later one.

Kang

Dr strange i think would sacrifice for rebuild the multiverse and close him forever

Someone important from Earth-616 or a variant

Kang will die

I'm thinking Red Hulk

Prolly Peter Parker