just haywire it to death
in all honesty, what i see wrong with all vehicles, which include the Monolith is the fact that an expensive and supposedly durable unit can be taken out with a single shot in the first place.
let's lay out some pros vs cons and we'll also see why Tau are such bastards currently with Riptides and Storm Surges
Vehicles
>Can be one shot with avast multitude of weapons
>can be shaken
>Can be stunned
>can be immobilized
>can have weapons destroyed
>cannot overwatch
>even many of the strongest can be melee'd to death by weak units
>can be glanced to death by weak attacks
frankly, they have so many weaknesses that their supposed advantages just make them gigantic free points.
MCreatures
>Can have saves
>can have FNP
>Cannot be shaken
>Cannot be stunned
>Cannot have weapons destroyed
>Cannot be Immobilized
>Can Overwatch
>can have invul saves and many other infantry benefits
>Can only be 1 shot by rarely seen special rules or weapons
Now, usually these advantages are offset, typically too much, by having a heavy pricetag, mobility, or limited shooting capabilities. Tau units however don't suffer from any of these three. They either have the range, have the cost, or have the mobility and in the case of the Riptide especially has all three.
What i believe should happen is vehicles have some of their weaknesses removed.
I would start by giving vehicles a saving throw vs Glancing hits vs attacks that are not AP2, AP1, or Destroyer. This would take effect prior to any other rules such as shots being modified (IE downgraded from penetrating hits). This would make it more enjoyable for players using vehicles (because sitting on your hands when being shot at sans a chance to save sucks ass) and make them more durable
I'd also increase the HP pool of all vehicles across the board by +1.
As a last change, if an Explodes result is scored it would instead change from Vehicle Destroyed to D3 HP are lost, the same as Super Heavies.