How do I make a object fall and then to original position?

I'm trying to make a enemy that has a floating hand and his hand have to go down and up again, to it's original position.

I'm using Instance Variables on Start of Layout and Every X Seconds> Define position> Hand.X, Hand.Y + 50), but it just teleport from a place to another.

Check it: fileport.io/avMw9LVQeQnw

Holy moly. Thank you very much!