I don't know if there's any point in discussing this scroll that won't be implemented anyway, but just for the heck of it:
First, some monster could be non-genocidable (like in Nethack). So slime creatures, ugly things etc. could just be given a no-genocide flag. The monster description should say this, of course.
duvessa wrote:What, specifically, should happen when the game tries to create a genocided monster?
What Chicken said would probably be the best approach. Create the monster, then kill it instantly (with no exp granted of course). Wouldn't this work for vaults? For random generation, another monster would be randomly generated.
tasonir wrote:Genociding draconian would leave zot pretty damned empty, if it applies to the entire class.
How big part of Zot draconians are placed by vaults (I have no idea)? Randomly generated draconians would just be replaced by other Zot monsters. Also I think in Crawl genocide should just apply to a certain monster type, not the entire class.
watertreatmentRL wrote:I think the way a good player would use the item you describe is similar to the way they would use the one I describe: They would hold it until they are in a situation where killing a particular monster will make an immediate, decisive difference. My scroll of instant KO is a bad item. It kills a monster instantly, totally cold. No wind up like Grand Finale, no resistance check. XP and so on don't matter. Your item has exactly the same problem, which is already disqualifying, and more.
Yeah, this is exactly one very useful way of using this scroll in Nethack. I think you're right in that in Crawl it would be the best use for the item. It sounds a bit boring.
I think I've changed my mind. A scroll (or any item you can carry around) of genocide would be boring (and probably OP). This should probably be a god ability. A god of genocide! No piety decay, with every piety star you get to genocide one type of monster. No other abilities granted. Assuming that genocide is technically possible to implement of course (re: vaults etc.).