We had a Rules As Intended question concerning Eusocial with respect to the Beetle trait "Sharing is Caring" and whether a 'system' in the rules wording meant a core system or if it meant 'things with an SP cost' or something else ... in part because of corner cases like making an Expanded Compartment tagged eusocial appears to be not RAI (because its non-sensical) while Pattern-B Hex Charges would make sense. And in the case of a weapon like the Pegasus autogun, it feels like you can't tag it as a weapon because it doesn't make normal attacks but it costs 1 SP to mount, so if that makes it count as a system would eusocial let people use the free action it offers?
Khepri Industrial Equipment - An Unofficial LANCER Expansion (Field Guide To Jovo Prelude) » Comments
Excellent question. Apologies it took me a while to answer.
Anything that is a System that can be installed is affected by Eusocial. Note that Eusocial only affects actions provided explictly by a system; Expanded Compartment doesn't provide any effect for eusocial because it just uses the standard Mount/Dismount action, not a bespoke action provided by the system.
As for Autogun, it is a Weapon (just one that happens to have an SP cost), but the Free Action it provides has restrictions on when it can be used (which is "at the end of your turn"). RAW, a Beetle with a Eusocial Autogun would allow for allied characters that are adjacent to it to fire at the end of their turns. Now, that does raise the problem of the Beetle Autogun Death Ball, which is probably more of a meme build rather than any effective strategy.
Update: So, this is a very reliable build but definitely not the star of the show. If you like playing a support damage role then this is cool but you need to expand a bit into other avenues or it can feel kinda stale. You're not making the big the plays and leveling a map but you are consistently softening up targets for others. I probably needed to build more utility into it. Also, i don't believe this is in the PDF but when determining adjacency for eusocial, we made sure to decide the exact hex my size 1 was magclamped onto size 3 friend so others knew where to stand to use my abilities (e.g. am I on his back his right side/left side, etc.). Otherwise, mainly in tight maps, it feels too overpowered if I'm just adjacent to everyone my partner is adjacent to via handwaving that I shifted outside of my turn.
"Also, i don't believe this is in the PDF but when determining adjacency for eusocial, we made sure to decide the exact hex my size 1 was magclamped onto size 3 friend so others knew where to stand to use my abilities"
RAW/RAI, that's not necessary because a Rider occupies the same spaces as their Host, though yes it's very funky narratively. The wording is borrowed from how effects such as Symbiosis or Mule Harness are described. It's totally fine to House Rule Attached to work the way you've described, though (I presume Mule Harness/Symbiosis are worded the way they are for the purposes of being one less thing to track or book-keep for most tables). Regardless, always fun to see people playing with the stuff we've made.