Why? 1) People can use it to kill team members. - Pretty self explanatory. 2) It ruins the pvp aspect. - People just spam lava on the islands (which are already quite small) and on pvp they just put it under your feet (meaning that people who have tons of lava are more likely to win) 3) It does unbalanced amount of damage. - While the new PvP mechanics got added and the PvP became bit more slow-paced, lava still makes huge amounts of damage very quickly. 4) The new PvP mechanics. - We should enforce people to make use of the new PvP mechanics (like the new arrows, lingering potions, elytra etc.) instead of lava. 5) The new update was made to make PvP require more skill, but I would not say that putting lava is really a skill.