Cast to Reference
I know it's a silly question, but every time that I'm going to cast to something that's not the player I don't know which thing goes as an object reference for cast to. Edit: Another screenshot due to everybody keeps focus on warning
You pass in the object reference that you want to cast to.
For example I'm guessing your Fire_Lantern is most likely an Actor blueprint that you made. Any single instance of that fire lantern actor that's in the map can be passed in to Cast to Fire Lantern.
Now there are numerous ways you could retrieve an instance reference to an Actor of type Fire_Lantern. It could be done using the Begin/End Actor Overlap events within blueprint Actors or perhaps you have a static number of Fire Lantern's in your level and you have a variable in your level blueprint for each Fire Lantern that you spawned into the level.
Here's a video that shows casting objects during Begin/End overlap.
I also notice you have a warnings in your compiler results tab that says Item is already a Fire Lantern so you don't need to have that Fire Lantern cast node.
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