Disciples of Crota
Eyes of Crota
Head out to the Terrestrial Complex. Get to the outside portion nearby the Last Array. Keep along the edge of the railing. You will see a Servant of the Eye worshiping an Urn. This Servant will not challenge you until you attack it. Take some time to clear out the other enemies in the area. Go and kill this Knight.
Approach the treasure that is sitting on the ground. Stealing the treasure will summon in a Tombship. This will drop a good number of Acolytes, Thralls and Servants of the Eyes. In the back portion, toward the back of the open area, you will find the Eyes of Crota.
Fight your way through the minions to reach the Eyes of Crota. With their Hive Boomers they can do significant damage at range. Go for the head to stun them to get some time.
Heart of Crota
Approach the Refinery from the Rocketyard. Head through it until you get to the Hive Seeder. Stop in this room as you will find the Servant of the Heart engaged in a ritual. Be on guard as the power of Crota will immediately poison the air around the Servant of the Heart. This will also loose a number of Acolytes and Thralls from behind you. Immediately start moving and fighting them. They will distract you as the Heart of Crota comes into the area.
The Heart of Crota will appear after a short delay of you fighting the Acolytes and Thralls. Fall back into the hallway you came in from. This will give you some needed distance and a chance to kill off the other Hive around you. You should take your time to deal with the Heart of Crota. Use the various pieces of cover to this end. Start with an Solar Damage weapon to cut through its shield. After that, aim for its head. This will give you the best chance for a quick fight.
Hand of Crota
Head into the Lunar Complex from the Mothyards. Make your way up through to the first dark room, just after the shutter. Do yourself a favor and clear out all the low level Hive in the area first. The Servant of the Hand is well hidden in this room so the chances of finding it early are moderately low. Head back to the starting door. Keep to the right and head for the corner. You will find the Servant of the Hand. This thrall will start moving if you get to close. Blast it away to lure out its master. Kill it will cause a number of enemies to appear.
Taking out the Servant of the Hand will unleash large group of the Hive. There are a number of Servants of the Hand, Cursed Thralls, Acolytes and the Hand of Crota.
This quest, along with the Urn of Sacrifice, has been removed from The Dark Below since patch 2.0.0. However all of the objectives can be found in their respective areas but killing them nets no reward as the Will of Crota Strike unlocks automatically after playing through the story missions.