Here's a simple tutorial on creating an item that can grant levels to your actors upon consumption. This method avoids any complex formulas and pesky common events.
Once you've enabled the plugin, it's time to create your items! They are extremely simple to create. Here's what you need to do:
1. Create an item that is consumable, and can at least be used from the menu.
2. Have the item target either the user or one ally. Unless you want a full party effect (a command which is already in the engine by default).
3. Make the formula HP Damage, and just put a zero in the box (for good measure).
4. Last but not least, add the following formula in your note field: <formula effect>
b.changeLevel(b.level+1,false);
</formula effect>
That's it! Now you have your level up item!
Extra Tips:
If you wish to create an item that grants more than one level at a time, all you have to do is change the 1 to however high of a number you wish.