Enemy "bands" would be a neat thing to add

[Guest]

Essentially they would kind of work the same as vaults,

There would be a file where groups of enemies would be already made and have a chance of spawning, for example

...O...O...
......T...... The "." stands for open floor
The T stands for a troll and the O stands for an Orc archer

This band of enemies has a chance of spawning on a certain level, they will move around in this position and when provoked, the Troll will break away from the group and hassle the player while the archers will pick the player off from a distance

I know some enemies like Orc captains already function like this, but I think this system will allow for more variance in fights and it would make the player rthink about how to tackle a group

[Patashu]

Sounds similar to Brogue's wandering dar packs.

[Derakon]

Some variants have the ability to spawn what I always thought of as "posses" of same-symbol monsters (so you could find a group of 'p' monsters or a group of 'W's, etc.). This occasionally made very dangerous groupings, and is probably not directly appropriate to Sil.

Vanilla also added monster associations beyond just the captain/underlings escorts, so e.g. Frost Giants usually show up with Frost Hounds. This might be more readily usable in Sil, since the groups you'd see are more controlled.

[debo]

Sil already spawns most monsters as homogenous packs of 2-3 monsters that have "group tactics". I think OP is asking to have heterogenous packs that also have deeper complementary tactics.

I've never looked to deeply into how the band-leader AI works for "captained" type bands (E.g. the orc captain already mentioned, Turkano, the Easterling uniques all "lead" heterogenous packs.)

[Infinitum]

Pretty sure the AI only checks for homogenous symbols; eg I've had solitary orcs/wargs happily charge past echother to get me in corridors. Pretty sure the "Escort" tag in monster.txt also spawns level-appropriate monsters of the same symbol. Could be cool to have sentient creatures cooperate and occur together, albeit the later already happens at random with sleeping/wadering monsters.

[Estie]

There´s only one band here, and that is ang.

[Guest]

If you'd like I could add frost hounds and Giants to Sil, they would not show up together like you mentioned but it would give you something extra to worry about