EXPANSION I - STORY MISSION 01: Fist Of Crota
Recommended Level: 24
Before starting this mission, you'll need to pick up the quest itself from Eris Morn, the new NPC who appears at the tower after you install the expansion. This is how you obtain the expansion quests (they don't automatically appear on the planets like regular story missions. Take the quest and shoot back to Earth to find the quest icon waiting for you.
Objective: Find the fist of Crota
Be careful when you spawn as there is a massive hive versus fallen battle going on nearby, and they are all level 24. Scoot around the outskirts of the fight until you see Omnigul; Will of Crota (a yellow health bar wizard). He is guarding the entrance to the area you need to pass through. You can take him on (he will disappear after losing about a quarter of his health bar), or you can just run past him into the building.
A word of advice before you decide though. The boss enemy at the end of this mission takes a fair whack of damage to bring down, so the greater your amount of rockets, powerful ammunition and character specials you have ready, the higher your chance for success.
If you do decide to battle, be wary as he spawns minions around him (thralls, acolytes, cursed thralls and knights) when he fights. He also has the usual shield, damaging wizard attack barrage and smokescreen abilities. Either way, head inside the marked building.
As you head deeper inside, you'll see a message pop up on the bottom left corner of the screen: "The minions of Crota have started a ritual." When you see this message, sprint ahead and lob a grenade into the center of the circle of acolytes and then open fire to interrupt the ritual. Once the three acolytes are dead, a yellow health melee knight carrying the blade of Crota will spawn in the center of the circle and sprint towards you to engage in battle.
Backpedal and aim for the head like normal against melee knights, jumping to the side to avoid it's strikes. This is good practice for the boss at the end of this quest. Maintain your fire and he should go down pretty fast. Try to conserve your special and heavy ammo for the end of the quest if you can here. When the knight dies, he will drop the sword for you to nab. Like last time (all the way back in story mission seven) the sword is all kinds of awesome.
You can still use RT to do a large AoE strike and RB to swing in an arc in front of you. The only downside? The sword is on a timer. You've only got exactly one minute of use for this thing so go aggressive. Push forward as fast as you can, killing as many enemies as possible. Follow the marker and you'll come to another open area and be ambushed by thralls, use the sword's AoE attack to clear them away.
Once the thralls are gone, three acolytes will appear and start chipping away with their weapons. Show them the cutting edge of your blade. About now is when the blade normally runs out unless you were very fast. The next group that appears consists of three thralls and two knights. Back away and use head-shots to get rid of both enemy types.
You remember that tunnel that lead to nowhere here? Well now it leads deeper into the bowels of the Earth. Descend through the tunnel to reach the Grottos area. When you arrive, you'll be greeted by a darkness area and a strangely empty room. Near the back is a glowing green ball of light. Approaching this will trigger the boss battle. Make sure you are fully loaded and your character's special ability is charged as this guy is a real pain (well, the ability he affects you with is).
Objective: Kill the Fist of Crota
As soon as you trigger the vortex, you will be afflicted by a disabling curse: A dark burden. What this does is prevent double jumps, triple jumps and gliding. While not sounding particularly threatening, it is far more dangerous than it appears. Why? Because the Fist of Crota uses a highly damaging smash rapidly that travels quickly in a line towards the target. Combine this with his fast movement speed and ability to jump and you've got problems. The main method for avoiding his smash attacks is to dodge to the side and keep moving (easier said than done, believe me).
And just because he's alone, don't think this is gonna be easy. When he drops to down to a third of his health, he will quickly summon several thralls and acolytes to support him and make your life hell. He also has the regular fast melee swings, which he will use if he gets close enough to you. Highly skilled players can sit on the threshold of his close melee and ranged melee strikes, so that he will keep swapping his animations.
Shooting him with heavy damage in the head (a full clip from a legendary assault... er, auto rifle for example) will stun him for around a second, allowing you to reload and re-aim. This is a great way to get through most of his health if you can get the timing down. If you listened to my advice earlier in the level and conserved your special and heavy ammo, you should be able to just blast him (and the minions he spawns) to bits with rockets/ mini-gun/ shotgun or specials.
If he does kill you and you have to reattempt the fight without your secondary or heavy weapons (like I did). Remember that you can wait, and your special meter will rise slowly by itself, at least allowing you to use your special during the battle. Once the Fist falls, the battle will end and you'll emerge victorious.