The Kuva Thralls in Warframe are the henchmen of Kuva Liches, powerful custom enemies who can torment Tenno as they try to figure out how to kill them. For anyone with an active Kuva Lich, finding a Thrall is easy. All you need to do is load into a mission at a node controlled by your Kuva Lich, and matching Thralls will appear during the mission.
They will be marked onscreen with a red waypoint, making it easier to track them, remove their health bar, and then kill them using a Mercy kill.
For new players, the entire Kuva Lich system may be new to you, so you'll go through everything you need to know, with plenty of links to other guides for more information. The first thing you will need to do is play the game until The War Within quest, after that you will be able to access the Kuva Lich content.
The first step after completing The War Within is to find a Kuva Larvling. These can appear randomly in any Grineer mission, but we prefer Cassini on Jupiter because it is a very fast capture mission. The Kuva Larvling will appear in the mission and a waypoint will appear. Follow the waypoint, then kill the Larvling and he'll drop to his knees. An icon will appear above their heads, telling you which weapon the Kuva Lich that will spawn will have. If you want the weapon, kill the Larvling with a Mercy kill. Otherwise, re-roll the mission until you get a weapon you like.
Now that the Larvling is dead, the Lich will appear and take over some nodes from your star map. These will be marked by a red Kuva cloud surrounding the planet and nodes. These nodes will spawn Kuva Thralls when you play missions on them, so head to one of them, find a Thrall and kill him.
We suggest that you read the two guides linked above, as they will give you a lot more information about the Kuva Lich system, which can feel quite deep when you first start playing.
