Infinity Countdown #4 is in stores today. It features the first appearance of the new character who is going to take central ficus in the upcoming summer series Infinity Wars. Over the past three previous issues a Dwarven smith has been forging armor in the one page lead up to the story. With Infinity Countdown #4 we see Requiem, the owner of the armor, take possession of it.
It is unknown at this time if she is a new character, or a previous character taking on a new name and armor.