Lord of the Hunt
This pack adds new single-player content set after the main game. The dwarf hunter Torvin returns for Talion's help with a new threat: five warchiefs who are taming dangerous wildlife for use in Sauron's army. It's up to Talion to stop the warchiefs before they can harness these deadly new threats.
This DLC is... kind of boring. It adds some new mechanics, such as mounted stealth and ghul control, and a couple of new mission structures. But the overall structure is exactly the same as the base game, just with a smaller amount of content set in an existing area. There wasn't anything new to explore, and the new stuff fits into the game effectively but doesn't stand out. Not to mention that the "story" doesn't even exist - what I wrote in the overview above is literally the entire story of the DLC. More bad guys are here, so kill them. Wow, so deep and original.
I would have vastly preferred that Lord of the Hunt's new stuff been added into the base game so that it would be available for the full playthrough of the story. With all my abilities unlocked and available, the nemesis system hardly even mattered - I wasn't dying or messing up enough for promotions or conflicts between captains to have any relevance. But had all these options been available from the beginning, they would have felt a lot more interesting and relevant. In particular, ghul control would have integrated really well, since ghuls only come out at night - the timing of your attack on a captain would matter as much as his weaknesses and the terrain.
The Bright Lord
After being unimpressed with the first DLC, I was looking forward to The Bright Lord. New story content set in the Second Age, playing as Celebrimbor fighting directly against Sauron? Yessssssss!
Unfortunately it wasn't anywhere near that interesting. This DLC uses the other half of the map that Lord of the Hunt didn't give access to, and the only difference is that Mount Doom is active so the air is smoky and ashen and orange. Again, there are new mission types and requirements to draw out warchiefs, as well as some new base abilities for playing as Celebrimbor instead of Talion. And again, these fall into the realm of "kinda neat" but set in such a boring story/mission framework that they don't feel like much. Really you're just doing the exact same thing as in the story: build an army, brand warchiefs, get the attention of the big boss and fight him direct. Plus Celebrimbor seemed like a power-mad bloodthirsty psycho who would be just as bad as Sauron if he had the power - maybe even worse - so that was eyebrow-raising.
The biggest new ability in The Bright Lord is the One Ring itself, which, when charged, gives you invisibility, unlimited arrows, unlimited finishers, and temporarily strips captains'/warchiefs' immunities. Fun, but also dramatically overpowered - when attacking warchiefs I'd just save up a ring charge, drop in on the chief, and spam unlimited unblockable combat finishers, completely ignoring the bodyguards and soldiers. It really trivialized the big fights - even the last one against Sauron himself, which was way harder than I expected but not for the reason you might think. I had to retry three to seven times at each checkpoint of the battle, but the difficult part was staying alive long enough to charge the ring. Once a charge was available I could just spam finishers safely. So I'm not quite sure how I feel about that last fight - parts of it felt epic, and it was a really difficult slog to get to the few moments of win button.
I actually wouldn't recommend either of the DLC mission packs. Yes, there is some neat new stuff, including new abilities and mechanics and mission types - but the structure holding them together is almost nonexistent. I would have vastly preferred that the new elements had been integrated into the base game to add more variety and options than walled off in uninteresting and tedious DLCs. Though I guess if you enjoyed the base game more than I did and you're not tired of the gameplay, the extra missions might be more your cup of tea.