potent sulfur cubes

Putting a potent sulfur block into a sulfur cube will make it hostile and deal half a heart, while also applying nausea to the target, similarly to how husk attacks deal hunger or strays give slowness. They still have increased knockback so you can use it to hit into other players to give them nausea. Potent sulfur cubes can also spawn naturally as a rare mob variant which you can put a block into for additional effects eg putting wool in makes it lighter and give nausea.