elegant way to attack and disable traffic to network node

what would be the most elegant way to block all traffic to local network node (computer) which may be connected trough LAN or WIFI with known IP address. Without reconfiguring the router. This should affect one particular node while allowing other to work. Attack is going to be performed from other computer on the same LAN.

So my question which is the most elegant way? IP address duplicate or MAC duplicate or ARP spoofing or anything else? Just point me out.