Chess Piece

Chess Piece. 

• Initiative. One chess piece, "the board," may move at initiative intervals of 5. One turn for each enemy creature above CR 25 or level 20. The board has one legendary action per turn.
• Attacking. A chess piece can occupy another creature's space. When a chess piece occupies another creature's space, they deal its "attack" damage. Creatures who share the same space as a chess piece take 100 damage at the end of each turn in combat.
• Resistances. At the start of each chess piece's turn, it may lose 100 hit points to end any effect on itself. Whenever a chess piece fails a roll, it may lose 100 hit points to succeed. If multiple chess pieces fail a roll from the same source, the king may choose to lose 100 hit points instead.
• Immunities. A chess piece's movement cannot be prevented by any means. A chess piece's form or features cannot be altered.
• Attacking a chess piece. Immediately after a creature kills a chess piece, another chess piece can spend its movement to move to the previously occupied space and deal its 'attack' damage to the creature, if it is within one square of it. Furthermore, the creature is exposed for 6 seconds (end of their next turn). An exposed creature takes double damage, loses all immunities and resistances, cannot be hidden, and cannot avoid attacks/damage in any way.

Special Traits.

• Pawn. 1 point, 500 hit points. When a pawn reaches the end of the chess board, it may choose to turn into any other piece and immediately take another turn.
• Knight. 3 points, 1000 hit points. Enemy creatures within 30 feet of a knight is vulnerable to all damage.
• Bishop. 3 points, 1000 hit points. There is an anti-magic field within 30 feet of a bishop.
• Rook. 5 points, 1500 hit points. Allied creatures within 30 feet of a rook is resistant to all damage.
• Queen. 9 points, 2000 hit points. A creature that reduces a queen to 0 hit points has its hit points reduced to zero.
• King. 0 points, 2000 hit points. The king has temporary 500 hit points equal to the number of points of pieces alive on the board. When the king dies, the board loses.

Attack. 

• Pawn. Melee Weapon Attack: automatic hit, reach 0 ft., all targets. Hit: 100 magical slashing damage. 
• Knight. Melee Weapon Attack: automatic hit, reach 0 ft., all targets. Hit: 200 magical piercing damage. 
• Bishop. Melee Spell Attack: automatic hit, reach 0 ft., all targets. Hit: 200 arcane damage. 
• Rook. Melee Spell Attack: automatic hit, reach 0 ft., all targets. Hit: 300 bludgeoning damage. 
• Queen. Melee Weapon Attack: automatic hit, reach 0 ft., all targets. Hit: 500 arcane damage. 
• King. Melee Weapon Attack: automatic hit, reach 0 ft., all targets. Hit: 100,000 times its hit point maximum, 100,000 times.