This was on my latest save with only the two main DLC's added on. On an early floor, I found a neat Dragonsbreath Caltrop Eruptor in a store which I bought. Later on I reached a fair-sized monster zoo, managed to plant it, and I was amazed to discover that the caltrop spewer...spat our more caltrop eruptors! It rapidly clogged up the entire zoo with extremely painful caltrops, eruptors, and corpses. I'd imagine this is a bug, or at least an overlooked bit of coding. From the looks of it, it seems to only be with Dragonsbreath eruptors erupting eruptors. EDIT: oh okay, so that's not a bug so much as them being incredibly powerful. ...so is there a way to close this thread or something?
Only dragonsbreath eruptors can spawn more eruptors. They do so approximately 20% of the time. For a level 16 trap, I'd say it's okay.
A 20% chance in a 9 square template will tend to diverge (the chance of one eruptor spawning more than one eruptor exceeds the chance of it spawning one or less). You're talking exponential growth here. Without bound. In fact the more the eruptors are triggered the less the chance of the chain reaction stopping. You definitely want an 11% chance or lower I think.