ID:143470
 
Code:Jutsu code
mob/Katon
verb
KatonHousenka()
set category = "Ninjutsu"
set name = "Katon: Housenka no Jutsu"
if(usr.Doing==0)
if(src.Chakra <= 14)
src << "Not Enough Chakra(15)!."
return
usr.Doing=1
src.Chakra -= 15
var/obj/Housenka/E1 = new /obj/Housenka (src.loc, src)
var/obj/Housenka/E2 = new /obj/Housenka (src.loc, src)
var/obj/Housenka/E3 = new /obj/Housenka (src.loc, src)
E1.loc = usr.loc
E1.dir = usr.dir
E1.name="[usr]"
walk(E1,usr.dir)//Makes it wlak in your direction
sleep(3)
E2.loc = usr.loc
E2.dir = usr.dir
E2.name="[usr]"
walk(E2,usr.dir)//Makes it wlak in your direction
sleep(3)
E3.loc = usr.loc
E3.dir = usr.dir
E3.name="[usr]"
walk(E3,usr.dir)//Makes it wlak in your direction
sleep(3)
src.Doing=0
del(E1)
del(E2)
del(E3)
else
usr<<"You are already doing something!"
if(src.Hp >= 0)
src.Death()

obj
Housenka
icon = 'FireBall.dmi'
icon_state = "Housenka"
density = 1
var/mob/O
New(location, owner) // this is for
O = owner
..()
Bump(atom/A) // when it bumps something
if(ismob(A)) // if it is a mob, damage the mob
world<<"[src] has hit [usr] with Houskena "
var/mob/M = A
var/damage = round(O.Ninjutsu*10)
M.Hp -= damage
del(src)


Problem description:it mob doesnt die when it has 0 hp

You have more problems in that code than I could try to solve. I'm not accusing you of using someone elses code but it really does look to be the situation here.

If you're serious about learning the DM language then start in the Tutorials section and read the DM Guide/Ref.
In response to Body
im not just familar coding big project
In response to Trane5
What's the difference between a 'big' project and that of a small one?

Nothing.

If you're not able to do both, I suggest you learn more from the Ref / Guides on this site.