Some boss script

-- Mob
local NPC_ID = 50003

function Boss_Spawn(pUnit, event)
    pUnit:SetUInt32Value(58, 0) -- Wanted this on spawn?
end

function Boss_BeginCombat(pUnit, event)
    pUnit:SendChatMessage(0, 0, "You shouldn't have come today.")
    pUnit:RegisterEvent("Chromie_ArcaneBlast", 5000, 0)
    pUnit:RegisterEvent("Boss_PhaseTwo", 1000, 0)
end

function Boss_PhaseTwo (pUnit, Event)
    if pUnit:GetHealthPct() <=75 then
        pUnit:RemoveEvents()
        pUnit:SendChatMessage(0, 0, "I see you're up for a little challenge!")
        pUnit:RegisterEvent("Chromie_ArcaneBlast", 5000, 0)
        pUnit:RegisterEvent("Chromie_ShadowBoltVolley", 10000, 0)
        pUnit:RegisterEvent("Boss_PhaseThree", 1000, 0)
    end
end

function Boss_PhaseThree (pUnit, Event)
    if pUnit:GetHealthPct() <=25 then
        pUnit:RemoveEvents()
        pUnit:RegisterEvent("Chromie_Model", 10000, 0)
        pUnit:SetMoveRunFlag(1)
        pUnit:MoveTo(-67.566589, 841.814904, 42.081596, 1.554467)
        pUnit:EnableMoveFly(1)
        pUnit:RegisterEvent("Chromie_ArcaneBlast", 5000, 0)
        pUnit:RegisterEvent("Chromie_ShadowBoltVolley", 10000, 0)
        pUnit:RegisterEvent("Boss_PhaseFour", 1000, 0)
    end
end

function Boss_PhaseFour (pUnit, Event)
    if pUnit:GetHealthPct() <=24 then
        pUnit:RemoveEvents()
        pUnit:SetMoveRunFlag(0)
        pUnit:RegisterEvent("Chromie_ArcaneBlast", 5000, 0)
        pUnit:RegisterEvent("Chromie_ShadowBoltVolley", 10000, 0)
        pUnit:RegisterEvent("Boss_PhaseFive", 1000, 0)
    end
end

function Boss_PhaseFive (pUnit, Event)
    if pUnit:GetHealthPct() <= 5 then
        pUnit:RemoveEvents()
        pUnit:MoveTo(64.066269, -814.885376, 41.173016, 4.707840)
        pUnit:Demorph()
        pUnit:RegisterEvent("Chromie_ArcaneBlast", 5000, 0)
        pUnit:RegisterEvent("Chromie_ShadowBoltVolley", 10000, 0)
        pUnit:SendChatMessage(0, 0, "I can't.. Keep myself in my dragon form, you're too strong!")
    end
end

function Chromie_Model (pUnit, Event)
    pUnit:SetModel(19537)
    pUnit:FullCastSpellOnTarget(15253, pUnit:GetMainTank())
end

function Chromie_ArcaneBlast (pUnit, event)
    pUnit:FullCastSpellOnTarget(51797, pUnit:GetMainTank())
end

function Chromie_ShadowBoltVolley (pUnit, event)
    pUnit:FullCastSpellOnTarget(15245, pUnit:GetMainTank())
end

function Boss_LeaveOrDeath(pUnit, event, pPlayer)
    pUnit:RemoveEvents()
end

RegisterUnitEvent(NPC_ID, 1, Boss_BeginCombat) -- on combat
RegisterUnitEvent(NPC_ID, 2, Boss_LeaveOrDeath) -- on leave combat
RegisterUnitEvent(NPC_ID, 4, Boss_LeaveOrDeath) -- on death
RegisterUnitEvent(NPC_ID, 18, Boss_Spawn) -- on spawn