Can you add damage reduction option from mortars onboard of AAI Vehicles: Ironclad? Right now it's too cheap to clear nests and explosive bugs. -70% damage reduction would nerf it nicely while still acting as good mid-game artillery

Unfortunately, nerfing other people's mods is the way to mark the mod as "incompatible" by the author.
I think it makes sense to contact the author of AAI Vehicles.

I also can't give all nests explosion resistance, as then the "vanilla" artillery will become useless. Currently there are 3 types of hives with resistance to explosive damage (regenerative, brutal and juggernaut). This already forces the player to use artillery selectively.

I see few options to "nerf ship" without touching other mods:

• Enable bitters swimming(only if there is no land path?) with, say, 25% of original speed => make it less leisurely, and forced ship to ship around which significantly decrese attack speed because of rotation speed

• Trigger base attack if there is no path to attacker => attack distant nest and suicide your base

• Make bitters to wildly disperse and run to another nest(or make new one) instead of dumbly waiting to die => attack distant nest and nest bitters attack would be much harder

• Spawn special short-living flying bitters (like swarm host in SC2) to attack anyone who attacked them => poke in nest and get deserved reaction; interesting option even without ships

Checking the path on every death is too resource-intensive.
However, the option with flying biters is quite possible to implement. However, if you do this on every death, it will destroy the stationary defense.
It may be worth creating a swarm only when nests or worms die. In this case, it is quite possible to check for the presence of a path and, if it does not exist or it is much longer than in a straight line, then do something unpleasant for the offender.

The current release is almost ready, it will not have this, but I think I will experiment with it in the next releases.

It may be worth creating a swarm only when nests or worms die.

Ye, swarm host idea is about defence option for bitters - that's why they short lived ones.
Can you check distance to nearest nest when dying? It is too resource intensive? If yes, then may be spawn non-attacking(do not participate in siege/base attack) five min living flyging bitters when aly nest/worm dies in near chunks => player would be forced to whitdraw after destroying one nest to cooldown for five mins.

P.S. You can expand on "defensive options for bitters" if you like that idea. Few examples: "burrow attack" - via spawning and teleporting(moving with 100500% speed for better mod compatibility) special version of banelings if enemy on creep; increase attack/move speed on creep; swarm host discussed previously; fast reaction worm spawning - if pollution is available, consume large amount of it and spawn worm on creep; a lot of options available to make it more challenging to attack nests instead of chore. So the map would be divided between "bitters", "engineers" and contested zone instead of "already factory" and "future factory")

"... five min living flyging bitters when aly nest/worm dies in near chunks => player would be forced to whitdraw after destroying one nest to cooldown for five mins.". - In fact, it already exists in standard and fixed Rampant. The player, even just being near the hives, is subject to attacks. When destroying something, vengeance squads can reach impressive sizes

"burrow attack" - This attack is already in development )
The main reason for its appearance is the abuse of waterfill. It is designed to overcome narrow ditches. If, when choosing the next point of attack, the squad sees that neighboring chunks contain disproportionately more pheromones, then a "digging" object will be created at the entry and exit points. A unit that enters an entry point spawns at an exit point after a few seconds. This attack, according to reviews, should be disabled in the settings. So far, this attack is not completely ready. It won't be in the next release yet.

At the moment, the idea of the mod is to force the player to make a defense of 3+ types of damage and arrange its supply. Attempts to make defense free-are consistently suppressed.
Opposition to the player "in the open field" is now at a sufficient level (the exception is the branch of magic in the RPG mod).

However, thanks for the ideas. I usually end up applying that come up in the discussions (when I have to counteract another abuse from the players). So this will be food for thought )

"burrow attack"

It's good to overcome walls too. To defend against that, you need to concrete base (increased time to spawn "digging object" if tile is artificial) and make empty space between walls (or they just burrow through your whole megawall) => make it ...||....||... instead of ...||||||||...

make a defense of 3+ types of damage and arrange its supply
Opposition to the player "in the open field"

All you need is "defend from player invading bitter territory" and you're golden :]

"burrow attack"

It's good to overcome walls too. To defend against that, you need to concrete base (increased time to spawn "digging object" if tile is artificial) and make empty space between walls (or they just burrow through your whole megawall) => force player to use less walls, like ...||....||xxx instead of ...||||||||xxx

make a defense of 3+ types of damage and arrange its supply
Opposition to the player "in the open field"

All you need is "defend from player invading bitter territory" and you're golden :]