I was kicking around some ideas for new Starfinder spells with my friend Conor last night. We were reworking many of them to either dial up the space-fantasy theme or to work around the rough edges of some rules. He'd suggested one spell that would deal damage in an area based on the number of electronics in that area--you'd just count the squares in the area with electronics, and more electronics-filled squares meant more damage dealt by the spell. I spotted a problem with this: there's an incentive for players to want to maximize electronics-filled squares for this spell, and an incentive for the GM to minimize the number of electronics-filled squares so the bad guys don't take as much damage. And those probably have to be counted on the fly. I could see players and GMs poring over maps, arguing over whether the computer depicted on the map fills two squares and whether a desk depicted on the map must have electronics in it (in a science fiction game, wouldn't most of them?). This would be a spell just about guaranteed to cause fights at the table whenever it was cast. 

This got us off on a tangent (or, by this point, the latest in a long series of tangents) about spells that would be virtually guaranteed to cause arguments around the table. Some ideas we had:

* One that provides a benefit based on the number of digits the caster has. ("Do bone spurs count as digits? What if they're on my hand? What if I can bend them?")
* A spell that interrogates a corpse, but only about the very last thought it had as it died. ("Wouldn't that always be 'oh, crap, I think I'm dying'?" "Well, maybe he wasn't looking right at his killer as he died.")
* A comforting enchantment that only works if the target's parents are alive. ("Are the skeleton's parents both alive right now?" "Hey, my species has about six parents--are you asking if they're all alive?")
* A spell that bases its duration on how long the player can do something. ("Okay, those enemies are paralyzed for as long as you can hold your breath, Greg.")
* A spell that affects whatever your character happens to be looking at or facing when the spell goes off. ("I wave my hands and shout as he casts his spell, so the monster has to be looking at me." "But my miniature is facing over that way.")
* A divination that only interprets languages the caster has heard before, no matter how long ago. ("No, really, I'm sure this language came up during an undergrad elective I had." "My aunt and cousins spoke that language in their home--are you questioning their culture?")
* charm person

If there's an RPG Writer Tip in here, it's this: don't create spells that cause fights.