If both kings get blown up, then whoever owned the Kamikazee will end up winning
Imaginary chess: if you could invent a totally new piece to chess, what it could it be?

If both kings get blown up, then whoever owned the Kamikazee will end up winning
ok

booooooomerang
is pawn that throws boomerang
boomerang explodes in a 2x2 area facing the direction in which it was thrown
can be thrown like the queen moves, forward backward let and right.

Unicorn:
It can jump, but it can't capture if it jumps over a piece.
Dragon:
Moves like a queen, but it can jump when it moves diagonally.

I have created too many new pieces already. So i put a very long prompt into a useless AI text app called inferkit and told it that i was the son of the Emperor of Scotland, and that i invented 7 new pieces to be added to chess. Here's what i managed to make the program say (screenshot if you like IDC):
1. The Quarter Soldier
General Description
The Quarter Soldier is similar to the Medieval Maid, and the Knight but can only move to one square diagonally and in one direction at a time.
2. The Quarter Robber
General Description
Similar to the King but it can only move to one square diagonally and in one direction at a time.
3. The King Cage
General Description
The King Cage moves in the same manner as the Queen. Unlike the Queen, however, the King cage is prevented from jumping over the other pieces.
4. The Bishop Crusher
General Description
The Bishop Crusher takes the "L"-shape of the Quarter Soldier, while retaining the same movement range. It cannot jump over the other pieces and does not move in the same direction as the King or the Queen, but it still retains the move distance of the King and Queen.
5. The Pope Hammer
General Description
The Pope Hammer occupies a line segment directly in front of the Queen (known as the "Enclosed Square") and can leap over any piece in front of it, but it cannot leap over a piece moving to its left.
6. The Bait of Many Fish
General Description
Similar to the Pope Hammer, the Bait of Many Fish takes the "L"-shape of the Bishop Crusher and moves in the same manner as the Rook, Knight and Bishop, while being capable of jumping over any piece in front of it and doing a few additional unique maneuvers.
7. The Curator
The last of the newly added pieces, the Curator has the most innovating gimmick of any piece. It can be placed on any of the previously occupied squares and later traded to the King, King Foyer or Boad when a captured piece is returned to that space. This gives the King another card to play when there is a sudden threat of capture from enemy pieces.
A great piece would the executed knight. Upon first capture, the knight would have his foot removed and so therefore, he would only be able to make the leg movement and the L shape would transform into I movement of only two squares in front of reverse direction.

Catapult: An option if your pawn reaches the end. Has the same moving capabilities as the King when it makes a move and can only check on it's first move. If it captures, than it can move again ONCE.

A piece that instead of taking the enemy's piece off the board, changes it's color. for example, I'm playing as black and I capture your rook, but instead of taking off the board the rook will turn black

A Cherub: It hangs about a foot above the board over the center squares, supported by a line and a coat hanger. It holds a lit candle. If any of its dripping hot wax touches an enemy piece, that piece is fried and removed (captured).

A piece that instead of taking the enemy's piece off the board, changes it's color. for example, I'm playing as black and I capture your rook, but instead of taking off the board the rook will turn black
Using your enemy pieces as your own exists in Shogi, the game of the Shogun.
Not exactly, what @DesgracadoJunior is describing is the exact same as the diplomat in diplomat chess.

The Castle
Moves like a rook but has a slightly different appearance. Bring this to your matches for an excuse to call your rooks "castles".

The Quantum Physicist
If adjacent to a friendly piece, it can open up a wormhole on any empty space for the piece to go to. However, the further away the wormhole exit is, the greater the chance the wormhole will collapse on itself, leaving the piece that was originally going to travel through the wormhole will immediately disappear. The probability of the wormhole collapsing can be determined using a die.
In this position -- assuming the knight is adjacent to the Quantum Physicist -- you will need to roll a die. If you want to take your knight to the first layer of arrows, you may do that without rolling. For the second layer, roll the die. If it lands on 1, your knight disappears. For the third layer, it's 1 or 2, fourth is 1,2 or 3, and so on.
You cannot have the Quantum Physicist teleport a piece to the sixth layer where it immediately vaporizes without any chance of surviving. Pawns cannot go through wormholes due to promotion being easier if not.
The Quantum Physicist moves like a queen but cannot capture. You may not use the powers of this piece on an opponent's piece.

The Trickster
Choose one of the 4 boxes of 6. The trickster can then capture any piece that goes in the chosen box. The opponent will not know which box was chosen. When the trickster captures a piece, they move to the blue square that was in the chosen box.

I would add the " Berserker".
it would move like a bishop and a knight combined. I would place it next to the king on the other side from the Queen. this would mean a 9x9 board with a pawn more per side.
it should have a devastating effect on middle game play. a true medieval maylay.

The Bomb.
The piece only exists as an alternative to "stalling out" of a lost game.
On his own turn, a player may choose instead of making a move to detonate his bomb, destroying the chess-board and all Pawns and pieces of both players. The move counts the same as resigning... the player who detonates his Bomb automatically loses the game.
Why would anyone do it?
Right now, a player who is losing badly has three options:
- Man up and resign.
- Play on until mate, wasting everyone's time.
- Stall out, wasting the opponent's time and possibly getting banned on a FPV.
Adding a Bomb piece gives the player a fourth option.
4. Boom. Take that. New game?
The Kamikaze
replaces one of your own pawns, but the opponent must not know which one it is at the start of the game. In online chess, the symbol for the Kamikaze would be a normal pawn with dynamite strapped to their chest. if you want to use this piece in a real chess game, simply place a piece of tape or something underneath the pawn of your choice, just make an indication that's invisible to your opponent.
What it does: the Kamikaze looks and moves exactly like a normal pawn, but it does not capture like a normal pawn. Whenever it captures an opponent's piece or gets captured itself, an explosion is triggered that destroys everything in a 3x3 area. It basically functions like an atomic mode pawn. With one major difference being that other pawns also get blown up.
The Kamikaze also does not promote like a normal pawn would, instead. Upon reaching the back row, the piece will explode the back row itself! All pieces still on that row will be gone and the back row will not be habitable for the rest of the game.
One more thing, if either king gets blasted by these explosions, they will be considered checkmated and the other player wins the game.
What if both kings are exploded at once?
Draw prob
I think it should be illegal to explode your own king, just like in atomic.
Makes sense.