Chess master

Set the board. When the chess master rolls initiative, he can summon one Bishop, Rook and Knight in unoccupied spaces around him within 30 feet. He also summons 1d8 pawns within 10 feet of him. Each chess piece has an AC of 15 and 10 hit points. 

Master of the game. The Chess master can move all of his active pieces. 

Pawn. Moves to an adjacent 5-foot square; any creature in the space is pushed to an adjacent space, and the piece then deals 9 (2d8) force damage to 1 creature within 5 feet

Bishop. The Bishop moves up to 90 feet diagonally. Each creature in the line must make a DC 16 Dexterity saving throw or take 18 (4d8) force damage. 

Rook. The rook can move up to 90 feet in a straight line. Each creature in the line must make a DC 16 Strength saving throw or take 9 (2d8) force damage and have its movement speed halved. 

Knight. The knight moves 30 feet foward and 10 feet sideways. Each creature that the knight passes must make a DC 16 Constitution saving throw or take  13 (2d12) force damage and be knocked prone. 

Queen. The queen can move to any location within 90 feet; each creature within 10 feet of the point the queen lands must make a DC 16 Wisdom saving throw, taking 26 (4d12) force damage on a failure and losing its reaction or half as much on a success. 

Place a piece. The chess master rolls a d10 and summons 1 chess piece within 10 feet of him. The piece summoned is dependent on the roll: 1-3 a pawn, 4-5 a bishop, 6-7 a knight, 8-9 a rook, 10 the queen. The chess master cannot exceed the number of pieces in the board game: 8 pawns, 2 knights, 2 rooks, 2 bishops, and 1 queen. 

Castling. When the chess master takes damage from a source, he can teleport to any rook under his control, and the rook teleports to his position.