They will still recruit hillmen spearmen and ax throwers, but two of the other thrall units will be replaces
Instead of Gundabad Orcs, Angmarrim tribal pillagers will be the Thrall infantry, comprised of local men and women of Angmar, loosely based off the “Angmarim” from LOTRO: Shadow of Angmar. They would serve as a spam unit to harass enemy economy.
And the thrall cavalry will be the “Elk Riders” in place of the Wolf Riders. They would also be lightly based of LOTRO’s angmarim, and will fill the niche of their light cavalry. They’re cheap, but can be easily lost to enemy pikemen, so like with the spiders of Don Guldur it’s best to recruit at least 30 of them to make them more effective against enemy infantry and archers.
Never the less the main purpose for both units is merely to distract enemy units while so stronger units get more time to spawn.