My favourite Minecraft Commands

Command 1

This command fills a forty by forty cuboid of tnt, which can cause a lot of lag if you explode it.

Command 2

This will give us a wither spawn egg, which any minecrafter knows, is one of the hardest and most destructive mobs. There is also an ender dragon spawn egg (replace wither_spawn_egg with ender_dragon_spawn_egg)

Command 3

This command will teleport every mob to you. Yes, every single one. Minecarts, Drowned, Items, Players, Zombies, Animals... (the list goes on and on).

This command will also cause entitiy cramming, which can kill the players, unless they are in creative.