private Item chooseRandItem(int slot, int tier, Random rand) {
        List<Item> itemList = Arrays.asList((Item[])items.keySet().toArray());
        Collections.shuffle(mats);
        Item chosen = itemList.get(rand.nextInt());

        if (items.containsKey(chosen)) {
            int randNum = rand.nextInt(100);
            int chance = items.get(chosen) - (tier - 1) * 5;
            if (randNum < chance) {
                chooseRandItem(slot, tier, rand);
                return null;
            }
            return chosen;
        }
}