Hey c.chan! To get your friends head you need the custom enchantment Decapitation 1-2. This enchantment you have a chanse get by doing /enchanter and purchasing a random enchantment for 45 tokens. -Issel.
Hi c.chan, in order to obtain your friends head you must have The decapitation custom enchant one your sword. You can obtain this from either using tokens to buy a random custom enchant or buying it off another player or /ah. Decapitation II will give you a higher chance of obtain your friend’s head upon killing them than having the Decapitation I enchant. Also, you need to kill them in the pvp arena, which you can access through /warp pvp. Hope this helped.