Minecraft wiki entry for Player_versus_Player, associated text: If you have lasted long enough to acquire endgame gear, the best potions are Strength II, Speed II (both splash) and Turtle Master (drinkable or splash depending on playstyle) and the best debuffs are Weakness and Slow Falling, both of which you should craft into arrows. This is because of the prominent use of explosive weapons such as ender crystals and respawn anchors, which are extremely deadly and can oneshot you on Hard difficulty, which most PvP servers are set to. Weakness makes it impossible for your enemy to punch an ender crystal to detonate it unless if they have Strength, and Slow Falling is used to increase the duration of the enemy being airborne when you hit them, making it easier to blow them up with your ender crystals (which do massively more damage to an airborne player in proximity as their feet are exposed to the blast rather than being blocked by the obsidian base) Both of these debuffs also neutralize the only other threat present in late game PvP combat, that being repeated critical hits with a Sharpness V sword and Strength II. The weakness counteracts their strength effect, and the slow falling counteracts their crits. Essentially, these debuffs hit two birds with one stone. Even if you're on Easy Mode servers with their weak crystals or aren't very good at having everything explode like Michael Bay, bringing these debuffs still make a huge difference in a battle as you cripple the damage your enemy could dish out.