After several rounds of negotiations, the other side had exhausted all their tricks with nothing left to try.
Tips
history
This idiom comes from Liu Zongyuan's Tang dynasty essay 'The Donkey of Guizhou' (黔之驴). A donkey was brought to Guizhou (where no donkeys had existed), and a tiger feared it until it realized the donkey's only skill was kicking - then ate it.