Lua TFS 1.3 solution to CONDITION_PARAM_SKILL_SHIELDPERCENT in healing spell

[Icaraii]

Hello,

I'm trying to put increased shield percent on a healing spell I have, but I can't seem to make it work.

local combat = Combat()
combat:setParameter(COMBAT_PARAM_TYPE, COMBAT_HEALING)
combat:setParameter(COMBAT_PARAM_EFFECT, 237)
combat:setParameter(COMBAT_PARAM_DISPEL, CONDITION_PARALYZE)
combat:setParameter(COMBAT_PARAM_AGGRESSIVE, false)

local skill = Condition(CONDITION_ATTRIBUTES)
skill:setParameter(CONDITION_PARAM_TICKS, 13000)
skill:setParameter(CONDITION_PARAM_SKILL_SHIELDPERCENT, 220)
skill:setParameter(CONDITION_PARAM_BUFF_SPELL, true)
combat:addCondition(skill)

function onCastSpell(creature, variant)
    local maxHealth = creature:getMaxHealth()
    local currentHealth = creature:getHealth()
    local healthGain = math.floor((maxHealth / 100) * 10)
    if currentHealth <= healthGain then
        return false
    end
    creature:addHealth(healthGain)

    local summons = creature:getSummons()
    if #summons > 0 then
        for i = 1, #summons do
            summons[i]:addHealth(healthGain)
        end
    end   
    
    return combat:execute(creature, variant)
end

I would like to know what I'm doing at this script. The healing works fine, also the effect and everything else, I just can't increase shield %.