help with fragmentation grenade

I have not tested or know if it works, it is just an idea:
create a block (it could have an animated "smoke" texture to fit the idea more) that is traversable, when the grenade (a projectile I suppose) hits an entity or when it hits a block, do:
If: get block at X Y Z (leaving it like this will make it appear in the center, add +1 in one or more coordinates to make the area, the procedure will be long) = air
do: replace block whit (block) and ignore the other
then say that when an entity collides with the block, it deals X damage to it
Now two things: if you want it to only do the damage, you must set the ticks of the block to 1 and put when it is updated tick "replace block in X Y Z with air"
if you want the visual effect is longer and you should enable the NTB in the block
create two NTBs, the example names will be:
Damage, smoke
in the part of when an entity collides with the block:
If: damage variable = true
do: do X damage
(By the way, when the block is placed, put the damage NTB to be true, it is normal for it to be false)
then in when update tick:
Set Damage to false, set Smoke get Variable "smoke" + 1, then put
if: smoke = (X ticks)
do: replace block at X Y Z whit air
I recommend that the X ticks be exactly the number of ticks that the texture animation lasts, and make the texture appear to be fading
I hope it's helpful and not too messy (:
A and potion effect: simply say that if damage is true (when an entity collides) it deals the effect
now I hope to help