The Valkyrie has a good hit points, similar to a knight, that deals damage in an area around her. Her splash damage makes her strong in deploying it in front of squishy troops. In a swing of her axe, she can instantly kills low health swam troops like Goblins and Skeletons. She can also kill Barbarians or put their health down if placed correctly.
The Valkyrie shines great because of its use of killing offensive troops behind a tank. She can be deployed next to the Wizard, Archers and Musketeer to save your towers and troops from incoming damages.