Kela De Thaym is the assassination target on Merrow, Sedna. She is one of the more challenging boss fights until you learn the fight, then it gets very easy - especially if you have the right tools for the job...

If you are farming Kela De Thaym for Saryn blueprints I recommend you go solo using Mesa or Mesa Prime and simply "press 4 to win"...

In order to gain access to Kela De Thaym you must first grind 25 Judgment Points by winning the arenas Nakki (Lv 40), Yam (Lv 60) or Vodyanoi (lv 85); if you successfully defeat Kela De Thaym and finish the mission you will however get 13 Judgment Points back. Grinding the Judgment Points from the arenas quickly become boring but the actual boss fight is worth the wait as it has some fun mechanics.

When you get to Merrow you first have to fight your way towards the boss. The enemies are only level 35-40 so it should not be a problem. When you get to the arena where you will be fighting Kela De Thaym you will notice a large circular platform on the ground with four small circular pads - step on top of the one with a light and shot at the turning disc on the wall - aim for the green light. This will raise the platform and start the fight.

Hint: Equip a Ignis Wraith (or normal Ignis) with Shred mod in order to hit the green light without aiming!

Phase 1:

Kela De Thaym is very agile and will jump from platform to platform while firing rockets - do not stand still, keep moving and bullet jumping to avoid damage! If you are playing Mesa, be prepared to press 4 and nuke the boss as soon as she finish talking and starts fighting. Some adds will also show up during this phase but you can just ignore them when playing Mesa - she will nuke both adds and the boss with her #4 ability.

Phase 2:

After Kela De Thaym has taken some damage she will jump up on a higher platform and a countdown for an Orbital Strike begins. Switch to your operator form before the countdown ends and quickly enter Void mode to avoid taking damage. As soon as the Orbital Strike ends, switch back to your warframe, stand on a glowing pad and aim for the green light behind the rotating disc on the wall - if you are playing solo you must quickly repeat this for all four pads to avoid another Orbital Strike; in a public group each member should stand on a pad and shoot the nearest green light.

These two phases repeat until you finally kills Kela De Thaym. Notice that during the fight more and more platforms will disappear making it harder to jump around avoiding damage. With Mesa you can just stand your ground, wait for the boss and nuke her with your Peacemaker ability.

Mutalist Alad V is the assassination target on Erris. He drops blueprints for the Mesa warframe.

In order to gain access to Mutalist Alad V you must first complete the Patient Zero quest and then craft a Mutalist Alad V Assassination Key with the blueprint you get from that quest. This blueprint requires Mutalist Alad V Nav Coordinates, which is a battle pay reward from Infested Invasions but can also be acquired from Orokin Derelict Survival and Defense missions.

Notice that Alad V is invulnerable when he has his collar equipped around his neck. During the fight he will throw the collar on a random player and mindcontrol him/her; this can wipe the entire team if a Warframe with a powerful DPS ability gets mind controlled!

I recommend using Loki to farm Mesa's blueprint as he is very fast and efficient for this fight. Use a stealth build and equip a powerful sniper rifle. Sprint/bulletjump/cloak your way through all the trash NPC's and hurry to the boss. When you get to Mutalist Alad V, cloak and place a Decoy or a Specter to keep him occupied - then aim with you sniper rifle and wait for the moment when he becomes vulnerable (i.e. when he removes his collar and either holds it in his hand or throw it at a Specter or team member), then quickly nuke him.