What you are trying to do is called multiselect.
Here's one way to do it, using lists:
Here's another:
P.S. Before going further, it is wise to rename Designer components to indicate their function and type, like btnCastSpell instead of Button23.
That will make the blocks much easier to follow and debug.
Also, if you use generic events, it is wise to include an ifNotAlreadyHandled test around your code, in case you want to add more of those component type with different purposes later on.