Tokkul is the only currency of the TzHaar residing in the underground TzHaar City. It is made from hardened bodies of dead TzHaar. Tokkul cannot be created by players. Tokkul is sometimes referred to as TokKul by some of the NPCs in the city.
The TzHaar Fight Pits activity, along with selling to the TzHaar shops (this can no longer be done due to an update by Jagex), was the first way to get Tokkul.
Tokkul is only received from the fight pits if you are its champion.
The amount of Tokkul you receive as a reward is based on the combat levels of all of the participants in that round.
The Fight Cave is the ultimate gauntlet for players proving themselves worthy of a Fire Cape. Players obtain variable amounts of Tokkul as a consolation prize depending on how far they progress before succumbing. Each time a player completes the Fight Cave, they will receive 16,065 Tokkul along with a Fire Cape.
With Guthan's set, a player may fight the Tzhaar kets for upwards of 50 minutes without banking, using the gear and inventory listed. With the minimum stats, a player can earn between 35 and 45k tokkul an hour, but with stats of over 80, a player may last over 1 hour without banking and earn about 50 to 60k tokkul an hour. Since the EoC update it is possible for a player with 80+ stats to earn over 100k tokkul p/h.
Interestingly, although Onyx is the most renowned item that can be purchased with Tokkul, it would actually be much more profitable to spend the 2,700,000 Tokkul on uncut sapphires. However, this would be much more time consuming as the store only stocks 1 at a time. Buying 2,700,000 Tokkul worth of uncut sapphires is worth ~60,000,000gp, or ~50,000,000profit over an uncut Onyx.
TokKul is spelled 'Tokkul', when in your inventory. But when you attempt to value something at a Tzhaar store it reads 'TokKul'. It is unknown whether this is an error in the coding of the game or there purposely.
With the personalised shop update, the price of the uncut onyx gem was increased by a factor of 9. The buying TzHaar-Mej spread TokKul into the sacred lava after The Brink of Extinctionand selling prices of other items were also somewhat increased, thus devaluing the Tokkul currency. This angered some players who were saving up to buy an onyx gem, and had therefore invested substantial funds in Tokkul.
The Mi-go, a race from the works of H.P. Lovecraft mine a metal called tok'l. The tok'l is used to create a Mi-go's "brain cylinder". This is remotely similar to the TzHaar in that TokKul comes from a TzHaar when they die. The name is similar, while the use is an opposite.
Due to an update, Tzhaar-Xils and Tzhaar-Kets drop up to a couple thousand tokkul now, as opposed to the previous ten or fifteen.
When looking at dropped Tokkul, the northern side of it appears totally invisible, except for the tops of the Tokkul, and when looked at from the side, it looks as if the tokens are cut in half.
It is advisable, should you have completed The Elder Kiln quest, to keep 50,000 in your bank, should you need to repair your TokKul-Zo in case of emergencies.