Wither Potions!!1

This mod adds the potion of wither, which should be a vanilla potion. Therefore, this mod is vanilla-like. That means the potion of wither can be crafted in the brewing stand with an awkward potion and a wither rose, just like in Minecraft Bedrock. Then, like vanilla potions, redstone can be added to make the potion last longer, glowstone to make it stronger, gunpowder to make it throwable, and dragon's breath to make it persistent.