Master of the Molten Flow

Head to the Flamewalker Shaman spawn area at 50, 40.3. Not every Flamewalker has a special ability, so kill any that do not cast their special within 5–10 seconds of engaging them — they will respawn faster if you loot them.

Pull a couple of Flamewalker Shamans and hit both with the Soft Foam Sword. Wait until they burn through their mana down to around 8%, then create a /sit macro and spam it as a Flamewave is about to hit you — sitting prevents dodging so the wave lands, causing the shaman to take damage from their own Flamewave and completing that challenge.

Engage a Flamewalker Hunter — yellow or yellow-red colored ones appear to have the Wild Barrage ability more often. Kill the hunter's dog first, then hit the Hunter with the Soft Foam Sword and back away; the stun lasts a couple of seconds. If the Hunter does not cast Wild Barrage within 5 casts, kill it and try another. Once Wild Barrage begins, hold the Up-Arrow and either Left or Right arrow on your keyboard simultaneously before the cast starts and keep moving this way throughout — this causes all spears to miss consistently.

Engage Flamewalker Sentinels and wait until one carries you away, then kill it. Hit them with the Soft Foam Sword to be safe. A reliable Sentinel spawn can be found at 41.59, 42.95.