"He contrived many ambushes to entertain us, like a fierce hunter for its prey."
One thing, it should be: "...like a fierce hunter for HIS prey."
Aside from that, there is nothing grammatically wrong with this sentence, but I think it could be clearer. "...like a fierce hunter for his prey" seems to denote fearsome, vicious, or aggressive-- not 'entertaining.' If you choose one direction (fierce) or the other (entertaining), it might read better:
"He contrived many ambushes to entertain us, like a crafty hunter luring his prey. "
"He contrived a series of ambushes to demoralize us, like a fierce hunter for his prey."