The pawns unionize.

A dragon roosts upon the rook at H8. This quadruples its power.

(This would be represented by a dragon atop 4 rooks)

Third possible move:

Suddenly, out of no where, all of the pawns remove their old fashioned postbellum hoop dresses and switch their icons to more form fitting, slender getups, smoking cigarettes and demanding the right to vote all as they march from left to right to left to right in the middle of the board and burn copies of Little Women in protest of being treated as little better than property by their husbands, the bishops, knights and rooks.

OP’s cat flips the board. Game over.

Fourth possible move;

The black pawn at F7 attempts to move down two tiles, proclaiming he is executing an en passant maneuver.

This causes the very old chess board, which has seen quite a lot of chess games and hates nothing more than the misunderstanding of the en passant maneuver, to open up its great maw, declare that the pawn has ‘activated his trap card’, swallow the pawn into sheol/hades underneath the board, and from there belch forth the mighty white eyes blue dragon, which takes up 2x2 in the center of the grid, is allowed 3 moves per each set of a black move and a white move, and appears to be hostile toward both white and black units.

Is the mobik cube allowed to be a piece

In the christmas spirit Nero Claudis sings “Padoru Padoru” at b4

Other possible move: The butterfly flaps its wings meekly, wasting a turn.

Elsewhere on the planet, 38 years in the future, a sentient alien species crashes the ship containing the last remnants of their wise and noble species due to an unexpected category 6 hurricane at their projected ‘safe’ landing zone.