Code
local integer random = GetRandomInt(1,100)
local unit dummy
local unit target = GetSpellAbilityTarget()
local unit caster = GetTriggerUnit()
if random <= ШАНС then
set dummy = CreateUnit(GetOwningPlayer(caster),'ДАММИ с ОГНЕННОЙ СТРЕЛОЙ',GetWidgetX(caster),GetWidgetY(caster),GetUnitFacing(caster))
call IssueOrderTarget(dummy,target,'ОГНЕННАЯ СТРЕЛА')
call RemoveUnit(dummy)
endif
set dummy = null
set target = null
set caster = null