Blackjacks are members' only melee weapons used in the Thieving skill to lure/knock-out certain NPCs located in Pollnivneach and the Thieves' Guild in Lumbridge. Blackjacking, also known as Coshing at the Thieves' Guild, is a method of Thieving training that primarily uses the blackjacks in Runescape.
There are three types of blackjack: ordinary, offensive (also known as attack), and defensive. Although the blackjack types are functionally the same and can all be used to lure/knock-out specific NPCs, they each provide different combat bonuses. Both the offensive and defensive blackjacks provide similar accuracy combat bonus with their corresponding wood counterparts. What distinguishes them from each other is the combat damage that each provides, with defensive having a very low damage bonus, while offensive having a reasonably high damage bonus. However, the ordinary blackjack has rather low combat bonuses in both damage and accuracy wise (the exception to this is the maple blackjack having the same accuracy with its maple counterparts). Offensive blackjack requires a certain Attack level, as well as a similar interval Thieving level to be equipped, progressing higher as the type of blackjack changes. On the other hand, the defensive blackjacks require appropriate Defence and Thieving levels in order to be wielded. The ordinary blackjack only requires a certain Thieving level to be wielded.To obtain blackjacks the player must first complete the blackjack section of the Rogue Trader miniquest. Once this is completed, the player can either buy ordinary/offensive blackjack or ordinary/defensive ones from Ali Morrisane and, if they want to switch types, can talk to the blackjack seller in Pollnivneach. They can also buy ordinary blackjacks from the trader near the kebab shop. The rubber blackjack is exclusive to the Thieves' Guild, and can not be used anywhere else other than the aforementioned. It may be bought from Dodgy Derek for 1 coin, or obtained from the advanced pickpocketing trainer, both residing at the Thieves' Guild.
To use the blackjacks the player must first have completed the Feud quest and have the necessary Thieving level to pickpocket either villagers, bandits, Menaphite thugs, coshing volunteers and the advanced pickpocketing trainer. Once the requirements are met and the player is wielding a blackjack, they select 'Lure' on the right-click menu. When away from other NPCs the player should choose 'Knock-out', though there is always a chance they will fail to knock-out the NPC. A successful knock-out will reward the player with a small amount of Thieving experience (with the exception of the Thieves' Guild NPCs). The player can then safely pickpocket the unconscious NPC for further Thieving experience.
Bandits and Menaphites cause damage for every failure, which can quickly add up. There is no bank in Pollnivneach, still there are a few options. You can boost your life point regeneration rate with items, familiars, and prayers like Rapid Heal and this will undoubtedly help reduce the frequency you need to eat. There is a kebab store in Pollnivneach which sells kebabs and super kebabs at a cheap price, however both are somewhat unreliable and buying from the shop is a slow process. You may also talk to Ali the Barman and purchase wine from him for very cheap prices. There is also a general store you can use to unnote food that you brought, which is the quickest option for obtaining food. Or you can simply use the magic carpet to return to a bank and withdraw food. Either way, the money from pickpocketing will easily cover all expenses. A ring of slaying or fused full slayer helmet makes it easy to return to Pollnivneach, using the Sumona option.
You can also move your Player-owned house to Pollnivneach, and then use the kitchen to heal in for free, or die in your dungeon, which will result in all stats recovered.
Coshing volunteers and the advanced pickpocketing trainer in the Thieves' Guild negates the need of healing, dealing damage of only 1 life point when failed. Thus this will minimise any cost of food needed. However, one will be stunned if a failed knock-out is executed.
Negating the failure
When you fail to knock-out a Pollnivneach victim, you will be attacked. If one was to quickly click pickpocket, the victim will negate the failure and will not attack. This is a great method to use when you are running out of food. Of course there is a chance of failure to pickpocket as well, which causes the victim to take off 50 life points. For this reason, a minimum of at least 100 life points is recommended before trying to knock out the victim. You could also attempt to knock out the victim again to avoid the stunning caused by failing to pickpocket.
Failing to knock-out a Thieves' Guild victim after luring them would result a 1 life point damage, following with a normal stun. This cannot be avoided even with high Thieving levels, or with chance-reduction items (such as the Ardougne Cloak and gloves of silence). Thus it is often considered as luck to successfully knock-out the victim and loot them. When one was to Lure and Loot the victim, the line "I'm teaching coshing here, not pickpocketing." would appear.
'Double Double Hit'
The 'Double Double Hit' is a technique used in blackjacking only applicable with Bandits and Menaphite Thugs at Pollnivneach. It is achieved when a Bandit/Menaphite Thug has been knocked-out, been pick-pocketed twice and then knocked out. After knocking the victim out, one should instantly right click the victim and pickpocket them. As soon, or slightly before, you hear the confirmation sound, right click on the Bandit/Menaphite Thug and pickpocket again. Then Knock them out again as soon as you hear the second pickpocket confirmation sound. The victim should lay on the ground still, allowing you to do an infinite 'Double Double Hit' (until the victim accuses you of pickpocketing him). Please note that this method is very difficult unless you have sound turned on. This is some of the fastest Thieving experience in the game, maximising at 260k to 270k per hour at the highest levels.
Where to train
The best place to train with blackjacks is always in a building, with a door and no other NPC. This is so your victim cannot escape to areas you are unable to knock him out, and the less space he has to travel the faster the process will be. Ali the Dyer's tent is a great place for Bandits, as it is small and has a ladder to escape the Bandit if he becomes aggressive.
Another place you can level Thieving at is the Thieves' Guild, using only their specially provided rubber blackjack. It is possible after knocking out the trainer to pickpocket (loot) a maximum of three times in one knock-out, though this is very difficult to achieve but very rewarding in experience. As soon as you've knocked down the coshing volunteer, instantly loot him. During the period when your head bows down (as with the burying bones animation), click loot again, which will result in an immediate second experience reward before the head is lifted from the first loot. Then, quickly loot a third time after you see your head lifting completely up as normal for the final experience reward before the victim regains consciousness.