Lua How to create spell warning area?

[Belfahar]

Hey everyone, how's it going?! First, I want to thank you for all the support I've been receiving! The server will be launched on the next 15th!

Today, I'm trying to create a spell that has that 'where it's going to fall' effect, like a warning for the player to have 2 seconds to dodge.

I've looked for some tutorials but without success. The spell in question is below.

local combat = Combat()
combat:setParameter(COMBAT_PARAM_TYPE, COMBAT_EARTHDAMAGE)
combat:setParameter(COMBAT_PARAM_EFFECT, CONST_ME_PLANTATTACK)

arr = {
    { 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0 },
    { 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0 },
    { 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0 },
    { 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0 },
    { 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0 },
}

local area = createCombatArea(arr)
combat:setArea(area)

local spell = Spell("instant")

function spell.onCastSpell(creature, var)
    return combat:execute(creature, var)
end

spell:name("abyssador poison wave")
spell:words("###87")
spell:isAggressive(true)
spell:blockWalls(true)
spell:needLearn(true)
spell:needDirection(true)
spell:register()