We made it! Now it’s a playable 18-card game.
The final rule link:
https://docs.google.com/document/d/1jRZryJ5_2V7hrNvwyZp771_QTSlCPHW6PKRKy9lvYT8/edit?usp=sharing
And we name it as Holmgang : the hidden!
Holmgang is a duel practiced by early medieval Scandinavians. It was a legally recognized way to settle disputes.[1]
I wish to address some changes during the development period.
1.Magic Shield card now has a new name “Magic Protection” to distinguish from Shield Attack.

2. No in-hand card for Judge
Solution: Draw a card from the discard pile
3. Strike-Back card is now a Defense card

- Cast each card’s function in a new sequence
Magic Shield → Mist → Thunder → Shield Attack → Ragnorok → Basic Attack → Strike-back

I sincerely wish to thank my partner Yanci for walking with me down this path and making this silly idea a playable game. Many thanks to Prof. King, and lovely playtesters Linda Chen and Steven Fang.
[1]https://en.wikipedia.org/wiki/Holmgang