Protect this! If you fail, your belongings go boom!
1. Get rid of any obsidian near your enemies castle/fortress/house
2. Place this by your enemies fortress.
3. Run like heck, because in 15 seconds, it goes boom. You cannot disable the nuke after it has been placed.
4. Look, and you should see flames spewing at you if you are close (~16 blocks?). This is supposed to happen to warn players and stop them from getting close.
5. Get to a safe place and look at the fortress
6. When the nuke goes off, watch it explode.
7. Loot the place and kill the weakened players.
8. Show them who the best Minecrafter on the server is!!!!!
(You could also use this to mine, but that is irrelevant)