Another method to acquire them is to negotiate a deal you can make with NPC Watson on RS gold Hosidius House. Watson will trade you his Master Clue Scroll for four other scrolls: Easy Medium, Hard, and Elite. This is a great method to discard scrolls that you are unable to complete. If you're stuck in a puzzle, you can give it away to Watson and farm for another one to begin with.
There's also the chance that you'll receive the Clue Scroll drop from skilling. The probability of getting one is contingent on the quality of the material that you are working with. In the case of woodcutting, for instance, when you are woodcutting, you will be able to collect Clue Scrolls more often from Yew trees than other ones. Also, when you are Mining for instance, you'll receive more clues coming from Runite rock than from Iron. In the course of skilling, you will have the following odds: 28.5% chance to get Beginner or Easy Clue Scroll, 21.4% chance for a Medium one, 14.2% for a Hard one, and 7.1 percent chance of becoming Elite.
Another method to acquire Clue Scrolls (and possibly the most efficient) is to buy Implings that were caught in a jar. In the event of opening these containers, it could result in the possibility of a Clue Scroll reward. If you'd like quickly access the Treasure Trail of your choice then you should consider this method. The downside is that this option is very expensive. You'll need to pay an enormous amount if are looking to purchase adequate difficulty scrolls from jars.
While clues from this level are the most basic yet, there are a couple of drops, that can be very useful. For starters, you are able to choose a prize from the drop table that is unique at the rate of 1/24 for each drop you receive. Therefore, if you are lucky enough to get three drops, it gives you a chance of 1/8 of getting a unique.
Of course, if you are lucky, you might find three in one casket. The value of items in this table yields mostly from 10k to 100k however, there are other items, like the Rune the Scimitar Ornament kit (Zamorak) which could be sold for as high as 500k gold on the old school rs gold Grand Exchange. Other than unique drops, there's not much worth mentioning with these caskets.
