For the new Phantom rank, it would be cool to add some special kill effects to make it feel more powerful. For example, when a player gets a kill, the enemy could get strike by lightning. Another idea is to have a dark blast when the enemy dies, like a small shadow explosion. You could also add a spooky sound when someone is killed, like a whisper or ghost noise. These effects would make the Phantom rank look more awesome and worth to purchase or maybe something like this?
https://www.spigotmc.org/resources/killeffects-✴-54-epic-particle-kill-effects-✴.65879/
Orrr maybe this?
https://builtbybit.com/resources/reankills-kill-effects-and-actions.41171/