Rise Of Sauron campaign - Successfully complete all War Of The Ring campaign maps to unlock the Rise Of Sauron campaign.

Legendary mode - Successfully complete the War Of The Ring and Rise Of Sauron campaigns to unlock the Legendary difficulty.

Easy health - When playing as an Archer, Scout, or Warrior, return to the "Change Class" location, and change to a Mage. After regenerating your health, change back to your original class.

Special abilities - Use one of the following moves to perform the corresponding special ability:

Aragorn: Hold [Strong Attack] for five seconds, then press [Weak Attack] while still holding [Strong Attack]. This will activate Powers Of The Undead for healing over time. Note: This can only can be activated once per life.
Elrond: Unknown move. Water sphere that heals and protects from projectiles.
Eowyn: Press [Weak Attack], [Jump]. She will do an invincible front flip over opponents.
Faramir: Unknown move. Energy attack can be repeated quickly for multiple hits.
Frodo: Unknown move. Does not uncloak when using melee attacks
Gandalf: Unknown move. Lightning attack will hit multiple enemies. Wider fire attack.
Gimli: Unknown move. Powerful Longbeard Pound energy attack that cannot be interrupted.
Isildur: Unknown move. Energy attacks made more powerful by flaming "ghosts" that deal extra damage.
Legolas: Hold [Weak Attack] for five seconds, then press [Jump] while still holding [Weak Attack]. He will ride on his shield.
Lurtz: Unknown move. Arrows can pierce through enemies and hit others.
Mouth Of Saruman: Unknown move. Lightning attack becomes progressively more powerful as it spreads through a group of enemies.
Nazgul: Unknown move. Power Of Nine attack can be used in combinations with other energy attacks.
Saruman: Unknown move. Lightning attack does high damage to single enemies. Powerful fire attack.
Witch King: Unknown move. Terror Quake attack that can damage an entire battlefield of enemies.
Wormtounge: Unknown move. Spawns a bomb in his hand that makes him faster, stronger, and regenerate energy quicker before it explodes after ten seconds.

Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

War of the Last Alliance (5 points): Complete the training level.
Battle of Helm's Deep (25 points): Complete the Helm's Deep level in the single player "War of the Ring" Campaign.
Conquer over Isengard (25 points): Complete the Isengard level in the single player "War of the Ring" Campaign.
The Mines of Moria (25 points): Complete the Mines of Moria level in the single player "War of the Ring" Campaign.
Siege of Minas Tirith (25 points): Complete the Minas Tirith level in the single player "War of the Ring" Campaign.
Battle of Pelennor Fields (25 points): Complete the Pelennor Fields level in the single player "War of the Ring" Campaign.
Assault on Osgiliath (25 points): Complete the Osgiliath level in the single player "War of the Ring" Campaign.
Assault on Minas Morgul (25 points): Complete the Minas Morgul level in the single player "War of the Ring" Campaign.
All's Well as Ends Better (35 points): Complete the Black Gate level in the single player "War of the Ring" Campaign.
Assault on Mount Doom (25 points): Complete the Mount Doom level in the single player "Rise of Sauron" Campaign.
Siege of Osgiliath (25 points): Complete the Osgiliath level in the single player "Rise of Sauron" Campaign.
Fall of Minas Tirith (25 points): Complete the Minas Tirith level in the single player "Rise of Sauron" Campaign.
Battle of Weathertop (25 points): Complete the Weathertop level in the single player "Rise of Sauron" Campaign.
Siege of Moria (25 points): Complete the Mines of Moria level in the single player "Rise of Sauron" Campaign.
Razing of Rivendell (25 points): Complete the Rivendell level in the single player "Rise of Sauron" Campaign.
The Land of Shadow (35 points): Complete the Shire level in the single player "Rise of Sauron" Campaign.
Splintered Shields (15 points): Kill 100 enemies in one life as the warrior.
Blade That Was Broken (15 points): Score 30 hits on the combo counter as the warrior.
Blademaster (20 points): Kill 25 players as the warrior in any ranked match.
Eagle Eyes (15 points): Get 25 headshot kills in one life as the archer.
Rain of Fire (15 points): Kill 25 enemies in one life with the archer's fire arrows.
Marksman (20 points): Headshot kill 10 players as the archer in any ranked match.
A Knife in the Dark (15 points): Use the scout to backstab 10 enemies in one life.
Fire and Slaughter (15 points): Kill 25 enemies in one life with the scout's bombs.
Assassin (20 points): Backstab 10 players as the scout in any ranked match.
House of Healing (15 points): Heal 30 allies in one life as the mage.
Flame of Anor (15 points): Kill 100 enemies in one life with the mage's fire wall.
A Storm is Coming (20 points): Kill 15 players with the Mage's lightning in any ranked match.
Storm and the Lightning (50 points): Score the most points on the winning team in any ranked online match.
A Red Sun Rises (50 points): Kill 30 enemies in a ranked Team Deathmatch match.
Rings of Power (50 points): Capture 3 rings in a ranked Capture the Ring match.
Ride to Ruin (50 points): Capture 10 control points in ranked Conquest match.
Return of the King (15 points): Defeat 3 Nazgul as Aragorn in Minas Morgul ("War of the Ring" Campaign).
You Have My Axe (15 points): Kill 20 enemies with Gimli in any Team Deathmatch game.
You Have My Bow (15 points): Kill 20 enemies with Legolas in any Team Deathmatch game.
I Will Take It (15 points): Capture a ring with Frodo in a ranked Capture the Ring match.
You Shall Not Pass! (15 points): Defeat the Balrog as Gandalf in the Mines of Moria ("War of the Ring" Campaign).
No Living Man Am I (15 points): Defeat the Witch King as Eowyn in Pelennor Fields ("War of the Ring" Campaign).
Lord of Mordor (15 points): Defeat Gandalf as Sauron in the Shire ("Rise of Sauron" Campaign).
Lord of the Nine Riders (15 points): Kill 10 players in one life as the Witch King in any ranked match.
Never Toss a Dwarf (15 points): Defeat Gimli as the Balrog in the Mines of Moria ("Rise of Sauron" Campaign).
The Way of Pain (15 points): Defeat Aragorn as Saruman in Weathertop ("Rise of Sauron" Campaign).
Stupid Hobbitses (10 points): Kill 300 hobbits in the Shire in one playthrough ("Rise of Sauron" Campaign).
Mithril Armor (10 points): Complete any campaign level without dying.
Fellowship of the Ring (10 points): Complete a campaign level cooperatively.

Additionally, there are two secret achievements:

Unfriendly Skies (10 points): Get picked up by a Felbeast (Nazgul) or Eagle.
That Still Only Counts as One (10 points): Climb and kill an Oliphaunt.