There are different ways to do this, including dominating Orcs by exploring the vast open-world and encountering them as part of Orc society, or players can acquire Orcs and other items through the Market (in-game store).
All that fancy build up about the Nemesis system and then "Oh yeah, and there's a store, guys".
A shame, but Steam sale it is, then.
I remember this from the books.
"I'll deal with the Balrog in a moment, Frodo! I'm just going to open this lootbox first. There could be some phat loots in here, you know."