That mostly seems fine. Going off of how many inches of terrain are in your way might add a bit of depth and some flexibility to how several layers of terrain work. That said, I'm not seeing huge differences between this and the existing terrain rules. A piece of terrain that happens to be both dense and obscuring, for instance, seems to achieve a lot of similar results. Could you spell out some of the main benefits you're seeing compared to the 9th edition 40k
Defensible terrain/garrisoning doesn't make sense to me as written. A few things that jumped out at me:
* Not being able to garrison a building because half an inch of one wall is outside your deployment zone seems like it could be a pain. I get that you're trying to avoid using defensible terrain as a speed boost though.
* Garrisoning seems like it's basically embarking in a vehicle or fortification. This makes me think you ought to be able to embark/garrison after
you finish moving.
* Garrisoning means that my unit functionally isn't on the table, but the benefits of garrisoning include getting bonuses to the unit's saves. So how does that work exactly? If my farseer and some guardians are garrisoned inside a building, does that mean my opponent can declare he's shooting the farseer and functionally snipe him out? Does garrisoning with a farseer mean he can't use his psychic powers? How does the blast rule interact with a garrisoned unit?
* Can a garrisoned unit shoot?
* How about melee involving garrisoned units? Is my opponent considered to be within engagement range of every garrisoned unit if he's touching any part of the terrain's base? Do the garrisoned units count as being in engagement range of all enemy units? Does that mean that Jain Zar's rule that lets her make attacks based on how many enemy models are within 2" of her could potentially let her make an attack against 100 ork boyz that have surrounded a garrison?
* Really seems like leaving a garrison should be similar to disembarking: exit within 3" and then move normally.
* As written, it seems like terrain grants a save bonus against both melee and ranged attacks (similar to being light and heavy cover in the 9th edition rules). Just confirming that that's intentional.
* Definitely agree that swapping out "10 or more wounds" for the vehicle/monster keywords is the right way to go.
Overall, I'd be willing to try these out. I'm just unclear on how the garrison rules work, and I'm not clear on the advantages of this system over the current rules. Also, and you probably already know this, there were rules for terrain features as buildings in not-so-old editions of the game. Being able to destroy terrain features raised some questions, but those rules might be worth looking at for figuring out how garrisons work.
-the fact that you cannot Garrison after moving, or leave the garrison then move, represents the time and distance of movement that it should take you to move the models into, or out of, the building if the building were some other terrain type other than defensible. You gain a powerful defensive benefit by garrisoning, with the downside being the loss of the footprint of the unit on the battlefield for scoring and the loss of synergy from aura abilities - in this way, garrisoning works similarly to open-topped transports, except that the unit is still eligibile to manifest psychic powers and make melee attacks.
-yes, characters garrisoning may be attacked. In age of Sigmar, character protection is a -1 to hit, which Defensible terrain also conveys, so I may add a note that CHARACTER keyword units count as being within 3" of any other unit garrisoning the same terrain feature that they are. Thank you for finding that hole in the conversion.
-The charger is considered to be declaring a charge against all units garrisoning the building, and models in the charging unit within engagement range of the buliding are within engagement range of the unit within the building. In your example, Jain would be within 2" of all 100 orks, if all 100 orks were within 2" of the building Jain was occupying. A bizarre edge case, but the correct extrapolation.
-I strongly believe joining or leaving a garrison should take more movement than embarking or disembarking a transport, given the strong benefit it provides with few significant downsides.
-The -1 to hit from Dense Cover is explicitly only applicable to shooting attacks, but basic Cover can be conveyed against both ranged and melee attacks, correct. Bear in mind, charging prevents a unit from claiming basic Cover.
3.0 features core rules for destroying a building (it remains on the table as a terrain piece but loses Defensible and all units inside essentially make an Emergency Disembarkation and are killed on roll of 1). Most notably this is keyed to a once-per-turn ability granted to all Monster units. I believe this may or may not be necessary to incorporate into 40k
and I'm comfortable leaving it off for now.
The primary distinction between the aos
3.0 terrain system and current 9th terrain is a trimming down on the available types of terrain, better rules for Representative terrain pieces such as forests, a removal of some of the minutiae of the terrain rules and various traits, and an increase in the availability of impactful cover in a deadly system. In many cases as well it introduces downsides to 'turtling' in terrain features, since getting the maximum benefits from a piece of Dense Cover requires you to apply a to-hit malus to yourself as well, and garrisoning a piece of Defensible terrain removes you from scoring and auras.