Skill suggestions

[AquaTsar17]

I also intend to have some late-game enemies with immunity to physical damage.  How could I make Kineticism useful against them?

Well, you could always suffocate them (though maybe that's just a StarWars reference with all the "force" effects you have there). Obviously it wouldn't work on a creature without lungs, but you would have to concentrate for several rounds while you suffocate the target. This would leave you open to attacks from other creatures, so although it's "instant death" in a way it actually isn't since it takes some time and makes you more vulnerable in return.

Or a force wall... stop the physically immune enemies from walking towards you so you could kill them later (maybe by setting them on fire or something).

[Vanguard]

What about a skill to break your opponent's arms or legs as the level 6 or 7 tactics skill?

Something like:

Cripple: Make an agility check against your target's agility to see if you successfully take hold of them, and if you succeed, check your strength against their endurance to see if you successfully can break their limb.  If you pass both checks, the target's speed, strength, and agility are massively reduced.

What would be a good way to do an instant takedown skill that ignores how much hp the target has left?