Most, but not all, panthara require a trick to tame. Farm up some Fresh Talbuk Meat which is drops rarely from talbuks on Argus; approach your target; throw a Freezing Trap; Feign Death to lose aggro (this is essential for the meat to work); throw the meat directly on top of the panthara; tame quickly! Panthara that do not require this trick are Naroua, Sabuul, and the Shadow Stalkers in The Seat of the Triumvirate dungeon.
Located in Shadowguard Incursion, The Seat of the Triumvirate (Dungeon). Shadow Stalkers inside The Seat of the Triumvirate can be tamed without the use of Fresh Talbuk Meat.