It is a good complement ...
1 - please add a permission that automatically gives you the unselected effect.
example:
- the user has a predetermined particle effect.
* deatheffects.defaulth.flame
and if the permission is removed, it has no effect.
it's just a suggestion to customize the effects more.
2 - And add a command that the effects can make them appear momentarily anywhere in the world {x} {y} {z} {world}.