Buy OSRS Mud pie
The mud pie is a members-only item in Old School RuneScape. It is not a normal pie. You cannot eat it to restore Hitpoints. Instead, you equip it and throw it at other players in PvP. Each hit lowers the target's current run energy by 25%, rounded down. Mud pies do no real damage and have no effect on NPCs. When one hits, a pie dish drops under the target.
Mud pies are a fun way to slow down other players. Since they count as a thrown weapon, targets with high Ranged defence are harder to hit. The pie has a range of 6 tiles, or 8 tiles on Longrange style.
Making mud pies takes work. You need pastry dough, a pie dish, compost, a bucket of water, and clay. Then you cook the raw mud pie on a range. This needs level 29 Cooking and gives 128 experience. The pie can burn until level 63 Cooking. Buying mud pies ready to use skips all these steps.
The mud pie is tradeable, equipable, and noteable, but not stackable. It weighs almost nothing at 0.001 kg, so it is easy to carry into any PvP fight.