Combat
A capture in ChessVS is a fight. The attacker deals its ATK into the defender's SHLD, and unless the defender is already spent it strikes back. Both pieces can fall, one can fall, or neither.
Everything below follows from that one exchange.
When neither side wins
If the attacker's ATK does not beat the defender's SHLD, the defender holds and the attacker goes back to the square it came from. The turn is spent and the board looks untouched.
The damage is not undone. Both pieces keep the shield they lost, so the next attack on either of them starts from the wounded number — and a piece on 0 shield falls to the very next thing that touches it.
A Bishop attacking a healthy Knight is the clearest case. 2 ⚔ does not beat 2 🛡, and the Knight's 3 ⚔ does not beat 3 🛡. Neither falls, the Bishop walks home, and both now stand on 0 🛡. The move that looked like nothing happened decided both pieces.
Nothing is ever fully disarmed
Every piece always deals at least 1 damage, however worn it is. A piece can lose attack from fighting, but never all of it.
"When all else fails, the fists remain."
The Pawn
A Pawn always deals exactly 2 damage. It never gains attack from a card, and never loses any from fighting.
That means a Pawn captures any piece down to 1 shield or less, and can trade with far larger pieces once they are nearly finished.
"The pawn's strength was never in the blade."
The King
The King deals exactly 2 damage and carries 5 shield. It captures any piece at 1 shield or less, and survives its first fight against anything on the board.
The King is the hardest piece to kill and the slowest to kill with. It finishes wounded pieces. It cannot break healthy ones.
"A crown is armour. It was never a sword."
Classic Capture
A piece with no shield left cannot strike back. Any attacker that reaches it captures it and takes nothing in return.
"A guard once broken answers nothing."
The King and spent pieces
A piece worn down to 1 attack cannot hurt the King. The King can attack it as often as it likes, at no risk.
"Spent hands cannot reach a crown."
Pawn takes Pawn
When a Pawn captures a Pawn, the attacker wins and takes no damage. Attack and shield are ignored.
"Between pawns there is no duel. Only the first to move."
The Honeypot
If your King attacks a piece and loses the fight, your King is eliminated and the match ends immediately. This is always in effect.
Your King survives its first fight with anything. The danger is the second.
"The crown that swings can fall."
Next step
Every clash is written into the move strip with its own glyph. See Reading the Battle Record to learn how to read a match back.