The TzHaar City is a city located under the volcano on Karamja. The Fight Cave minigame is located in the northern part of the city, next to the bank. The local currency is TokKul. It is inhabited by various types of monsters. It is also the only place to buy an Uncut onyx with TokKul. You can also teleport to the city by using the Minigames Teleport in your spellbook and selecting the 'Fight Cave' option.
There are four types of monsters ranging from level 74 to level 149.
These monsters are not agressive, so they will not randomly attack you. The entire city is a multicombat area so attacking multiple TzHaar will result in death if not prepared. The TzHaar City is not a safe area so all items, except for the usual 3 (or 4 with the Protect Item prayer) will be dropped on the floor. The only safe area is the Fight Caves minigame, where the TzTok-Jad can be fought.
There are also a couple of NPCs like the TzHaar-Ket-Zuh (banker).