You can leave your Sister on Venus & they’ll only steal the credits you get from missions on that planet. So you shouldn’t be missing out on too much by ignoring the controlled nodes (you can always do the normal missions on those nodes too when clicked on, so not locked out of anything)

You may have more power to deal with them than you think though. The big thing will be going over the Lich/Sister system, mostly meaning you’ll need to get Requiem Mods for your Parazon as this is the only permanent way to kill your Sister

As others have mentioned, recruiting chat in-game or most of the Warframe Discords are usually willing to help with any of this if you need help too!

Very (VERY) basic overview of handling your sister if you wanted to take a stab (heh) at it.

• Liches/Sisters need a “passcode” to kill. You need the correct 3 Keys (Requiem Mods) & in the correct order to actually take down your Sister.

• Clearing Nodes, and killing the Hounds in these Nodes, gives murmurs which automatically unlock progress towards these Keys (Requiem Mods)

• You get the mods themselves from Requiem Relics, which drop from Kuva Siphons / Kuva Floods under the Alerts tab on the starchart. Just like Void Relics, these relics need to be opened in Void Fissures (located under the Void Fissures tab on the starchart)

• These mods are equipped to the Parazon (slot specific. ABC is different than CBA).

  • You don’t have to know if a mod is valid to equip it. This menu at the bottom only tells you what the valid mods are too, not the order.

• Clearing nodes, and killing Hounds, also enrages your Sister causing them to eventually spawn.

• Damage the Sister, then stab them to test if your mod is in the right place. If it is, you proceed to try the second, then if correct again, the third.

  • If the mod is in the wrong place, the Sister levels up, gives you murmurs, then removes themselves from the planet you’re on & goes to the next.
  • This is good though! Because this means we know our mod doesn’t go in the spot we tried (higher chance of the next mod we try in that slot being correct)

• Repeat the above until you have all the mods and have them in the correct order to kill you Sister. This will then send them to a Showdown located in Railjack. The enemy level here is also capped at 65.

  • Kill them at the Showdown to either claim their weapon or their person.