Spellcasting in the adapted Ghostbusters system

In the Ghostbusters system everything you try to do (beyond normal mundane things like tying your shoe -- unless you're playing a three-year-old) is given a difficulty number.  You roll the number of dice in the related Trait and try to equal or beat the number.  Why not so with spells?  So my spellcaster  has a Brains/Intelligence of 5.  Let's pretend I have a list of spells, divided into ranks by their relative power.  To steal some from D&D, a Magic Missile might be a Rank I spell, a Fireball a Rank III.  Just for a baseline test.  So I'll decide, at this early juncture, that Rank I spells are difficulty 5, Rank IIs are 10, and Rank IIIs are 15.  Now my spellcaster wants to cast Magic Missile.  Or: let's give it a different name like ... Arcane Bolt.  I dunno.  So I roll five dice, including the Ghost/Skull Die, and I get a 12, with a 4 on the Skull Die.  That's more than 5, so it's a success.  The spell goes off, and the nature of the spell means it automatically hits its target.  No Skull, so yay for me -- no complications or other things that will help my opponents.  But what if later I try a spell I barely know, or maybe one I've just learned recently from a musty old scroll I brought back from an adventure -- Claddadh's Thundering Inferno, a Rank III spell.  So my target number is 15.  Again, I roll four dice plus the Skull Die.
Uh-oh, I rolled a six on the Skull Die, which is the skull. It counts as zero and means I'm due for trouble, regardless of whether I succeed.  The rest of the dice total ... exactly 15.  Whew.  So, in the course of my first attempt to cast this probably ancient spell, I barely manage to keep it from burning out my cortex and instead it burns my enemies.  But wait: I rolled the Skull too.  The GM lets me know that the thundering ball of fire does indeed incinerate my degenerate foes, but also catches the old chest in the corner of the room, which, being it was actually an incredibly rare sculpture made of highly flammable but valuable material once used by some people who are all dead now, this probable archaeological treasure goes up in flames, destroying it and whatever nifty secrets it may have contained.



I think it's workable.