I think we should put down a revision exchanging some our crafts weaponry with heavy plasma weapons, just enough so we can determine combat effectiveness of the theoritical weapons without sacrificing the Tesla gun's. another option, we could do a revision to copy the fuselage of their Skyrangers, replace the engines with plasma vector systems and reactors, strip any capacity for re-entry and go from there.
The mountains are a tricky, tricky situation. Tanks with tracks aren't effective at all there, and the enemy has already proven that mechatronic equipment works there, but I'm all for going for a different philosophy than heavy, heavy walking tank if we want to go for that. In the meantime, I'm gonna propose an astral design.
Design: Force Screens
Force Screens are the first result coming from trials for defensive measures that utilize Astral projection. Although the original design could theoritically be "powered" through non-humanoid means, the lack of access to such resources outside of test environments means it is a moot point.
The Force Screen is a system of conduits, a quas-capacitor, ventilatory systems and other support equipment designed to be retroactively attached to our field equipment to generate a spherical "anomaly" of high-energy Electromagnetic forces.
This Anomaly effectively catches high energy particles (such as laser weaponry) and ballistic projectiles and then begins shearing it apart, layer by layer, until it ejects out as a stream of plasma or a low-energy emission of infrared light depending on what collided with it, (in addition to a small, concentrated blip of Astral Energy). If an object is going too fast or an oncoming stream of energy is too strong, some of it may get through, this is by design to prevent situations where the capacitor is instantly filled up. HEDP or HEAT rounds will lose the majority of their effect here, as they will penetrate the shield and then splash our tank with their molten metal instead of the cabin. The generated field is referred to as an anomaly until such a time when the design team can put a name to it without breaking down into violence. We know how to generate it, how to shut it down, and the physics behind it, and that is all that matters. The term "Force Screen" is a soldier-oriented term that is the most accurate considering circumstances. Due to how the screen is layered, it cannot intersect with another screen, and fire coming from inside the screen will not be deflected to create some sort of hellish pinball machine from hell. Slow objects going under 50 miles an hour are not caught.
Not only does this generate waste heat, but also a sort of entropic energy. It cannot be vented into the air fast, but it can be re-routed into the "quasi-capacitor" fore storage until our ventilatory systems can catch up. The capacitor essentially a giant brick of specially treated metal the size of a small engine block, and it is recommended to shut the shield down before it "overloads" and detonates.
While one psionic individual may not be enough for the entire system, it uses a series of emission and broadcast fields to essentially "siphon" off of other individuals in play, allowing the shield to be engaged when sufficient persons are nearby (typically 8.)
This system was designed with the Ettin in mind, but it can also be deployed to other tanks, and possibly any other vehicle, although two or three individual systems converting sections may be required.