And your idea of a one-time enhancement Trance (spell) appears to be an excellent idea of something different while not being too powerful.
However, I think the rules need some clarification.
In particular, the army 'Hologram' appears underpowered rules-as-written. You gain the ability to suicide your queen to teleport your king. Useful, but only so much. You can't use it offensively (teleporting your king to the front lines is not smart) and if you use it to get the king out of check you're already in a bad way, and probably only delaying the inevitable.
Meanwhile, you loose the ability for the queen to capture--but it can still be captured, apparently. So the queen is essentally useless. (The rules specify only that the queen cannot capture. All other rules being the same as chess, that means the queen can be captured. A queen that cannot capture or be captured is useful as a blocking piece--is that what you meant?)
The Trance is not that powerful, only allowing the queen the ability to capture kingwise. (If the queen is uncapturable, this is very powerful.)
I'm left with the conclusion that you must have meant the queen cannot capture or be captured.
I strongly encourage continuing work on this....I love the idea of 'choosing different armies'!
Sirlin's Chess2
Betza's Chess with Different Armies
Fantasy Grand Chess
And your idea of a one-time enhancement Trance (spell) appears to be an excellent idea of something different while not being too powerful.
However, I think the rules need some clarification.
In particular, the army 'Hologram' appears underpowered rules-as-written. You gain the ability to suicide your queen to teleport your king. Useful, but only so much. You can't use it offensively (teleporting your king to the front lines is not smart) and if you use it to get the king out of check you're already in a bad way, and probably only delaying the inevitable.
Meanwhile, you loose the ability for the queen to capture--but it can still be captured, apparently. So the queen is essentally useless. (The rules specify only that the queen cannot capture. All other rules being the same as chess, that means the queen can be captured. A queen that cannot capture or be captured is useful as a blocking piece--is that what you meant?)
The Trance is not that powerful, only allowing the queen the ability to capture kingwise. (If the queen is uncapturable, this is very powerful.)
I'm left with the conclusion that you must have meant the queen cannot capture or be captured.