Hey glo!
You can only combine magic pins, and only of the same type (fireworks with fireworks). What it does for fireworks, invisibility and pirate costume (and I assume inferno) is make the effect last longer, which goes up by the amount of pins you combine. The most you can combine is five, which is then called a "hive-star" pin in VMK LOL
I've heard that combining teleportation just decreases the amount of time you have to wait between uses.
Storm magic isn't tradeable, so you can't combine that anyway. Some people had gotten two Buried in Treasure pins during the code mix-up, but not sure if combining those does anything?
To combine, you take off the pin, highlight it, click "combine", then highlight your other magic pin of the same type. If I remember correctly, I think it gives you a message asking if you are sure you want to combine, because once you combine them, you can't ever separate them again. Click ok, put the pin back on, activate and enjoy!
