LUA help, how to make npc cast a spell at a certain HP???

[pioneer1337]

Well, I'm making a custom boss for my server and I want him to cast enrage on himself at 40% health and I want him to only do it once. This is how I have my code written right now:

function Boss_Enrage(Unit, event, miscunit, misc)
               if Unit:GetHealthPct() == 40 and Didthat == 0 then
                         Unit:FullCastSpell(34670)
                         Didthat = 1
            else 
            end
end
 
RegisterUnitEvent(9999999,1,"Boss_Enrage")

Well I tried this and when he got to 40% hp nothing happened. I was thinking it might have something to do with the 1 in
RegisterUnitEvent(9999999,1,"Boss_Enrage") but I dont know. Please help?

[pioneer1337]

Does anyone know?

[Lich King]

Change to this:

function Boss_Enrage(pUnit, Event)
 if pUnit:GetHealthPct() < 41 then
  pUnit:RemoveEvents();
  pUnit:FullCastSpell(34670)
 end
end

[Gastricpenguin]

Thats because when the mob enters combat, it will only check the HP once at the start of the fight. Its better to make 2 functions. Here is the proper script:

function Boss_OnCombat(pUnit, Event)
 pUnit:RegisterEvent("Check1",100, 0)
end
RegisterUnitEvent(9999999,1,"Boss_OnCombat")
 
function Check1(pUnit, Event)
 if pUnit:GetHealthPct() <= 40 then
  pUnit:RemoveEvents()
  pUnit:FullCastSpell(34670)
 end
end