Western Plaguelands
Just past the Bulwark in the Western Plaguelands, you’ll find Felstone Field. There are a ton of weaker, undead mobs that are easy to kill and drop a ton of Runecloth. These mobs range in the mid-30’s, so soloing them isn’t hard either. They also spawn rapidly, so you don’t have to worry about waiting or other players.
In the Northwestern Plaguelands is the Scarlet city of Hearthglen. Here you’ll find some pretty easy elites that range from 53-56 and are just higher level versions of the Scarlet Priests, Scarlet Sentinels, Scarlet Paladins, and so on. They do drop a lot of Runecloth, but the reason to head here is for the other drops. They have a very good drop rate for green, blue, and even epic items that sell great on the AH.
On your way through Hearthglen, you’ll find a tower where the Scarlet Spellbinders are. These are the only mobs in the game that drop the formula for Enchant Weapon – Crusader. This formula alone will sell for over 200g on the AH and is pretty rare. You do have to watch for other players here, as the mobs spawn at a fair rate, the drops aren’t always as fast to spawn.
In the eastern-most part of the Western Plaguelands, you’ll find The Weeping Cave. In this cave, you’ll see the Rotting Behemouths and the Decaying Horrors, which range from level 55-57. These mobs are easy to kill and have a really great drop rate for all sorts of items. You’ll find the recipe for Greater Nature Protection Potion here, which sells for about 100g. The drop rate for this potion is only about 1 per 100 kills though, so you might have to grind for a bit to get one, but it’s worth it!