连续合成衰减：同款装备连做成功率逐次下滑

local function craft(actor)
    if math.random(1, 100) <= 10 then
        giveitem(actor, "烈火剑法", 1, 0, "合成")   -- 概率恒定可脚本刷
    end
end

local function craft(actor, combo)
    local rate = math.max(math.floor(10 * 0.8 ^ combo), 2)
    if math.random(1, 100) <= rate then
        giveitem(actor, "烈火剑法", 1, 0, "合成")
    end
    sendmsg(actor, 1, "本次成功率 " .. rate .. "%")
end
craft(actor, 5)                     -- 连做第6次，成功率滑到3%