About Multicast Delegates

Multicast Delegate
Delegate that holds the reference of more than one method.
Multicast delegates must contain only methods that return void, otherwise run-time exception will be thrown.
Example
delegate void DelegateMulticast(int x);
Class ClassX
{
    static void A(int x)
    {
        Console.WriteLine("Hello A");
    }
    static void B(int x)
    {
        Console.WriteLine("Hello B");
    }
    public static void Main()
    {
        DelegateMulticast func = new DelegateMulticast(A);
        func += new DelegateMulticast(B);
        func(1);             // Both A and B are called
        func -= new DelegateMulticast(A);
        func(2);             // Only B is called
    }
}
Description
As you see that there are 2 methods named A & B with one parameter and void as return type.
Create delegate object
DelegateMulticast func = new DelegateMulticast(A);
Then the Delegate are added and removed using the += operator and -= operator resp.