This legendary crafting material is easy farmable, because of an 100% obtainable rare spawn.
This legendary crafting material can be farmed from Ssthrass a rare monster in Dahlgur Oasis, which you can reach very fast.
1. Open a game in campaign mode at low difficulty level and with the Act2 Quest Blood and Sand
2. Take the waypoint to Dahlgur Oasis and run to the north. At the bridge you will find Ssthrass.
3. Enter the Ancient Waterway, because there you get a checkpoint.
4. Leave the game.
1. Set difficulty level as high as possible, test around which torment level you can afford.
2. Start game and take portal to your last checkpoint.
3. Leave the Ancient Waterway to Dahlgur Oasis.
4. Infront of you, there will be now Ssthrass. Kill him and loot.
5. Port to town, leave game and repeat.