Trick...

...or treat?

A cautionary tale.

Brave Trick or Treaters
Show no distress;
I'll give you some sweets 
If you can beat me at chess

Brave Trick or Treaters 
Your defeat could be quick;
After 600 years
I've learned the odd trick

Brave Trick or Treaters
It won't go your way;
Lose the chess game - 
There's a forfeit to pay.

Brave Trick or Treaters
We welcome your call;
Others have tried here
And I've eaten them all...