The quest involves killing Redania’s King Radovid, a cruel ruler who torments his people. It takes place in the southwestern part of Novigrad, and you will be accompanied by Dijkstra, Thaler, and Roche to try and deal with the king on a permanent basis.
The Reason of State quest in The Witcher 3 will begin once you complete Blindingly Obvious. You have to then head to the Novigrad docks to meet Dijkstra, Thaler, and Roche in a seemingly abandoned warehouse.
Something important to note here is that you must bribe Dijkstra to get information about Emhyr during the Blindingly Obvious quest. Do not use force.
This will be during the third act of the game, and a lot will have happened by now.
You can begin the Reason of State quest once all of these prerequisites are done, but make sure to do the quest before starting On Thin Ice where Geralt takes down Caranthir and Eredin. Otherwise, you will fail Reason of State.
Meet your allies in the warehouse
Once you walk inside the warehouse, starting this quest, you will meet with your allies who discuss ways to put an end to King Radovid’s rule on Redania.
In case your game gets bugged at this point in Reason of State and you are unable to open the warehouse door, simply save and then reload your file.
Dijkstra formulates a plan that involves luring out Radovid, baiting him with the location of Philippa Eilhart. It is decided that Geralt will be the one to lure the mad king out.
At this point, you have a choice to make. You can either choose to lure out Radovid and kill him, or you can deny them.
The best choice for Reason of State is to go ahead with Radovid’s assassination and put an end to his rule.
Denying the plan will fail the quest and will lead to Radovid keeping his rule of Redania and winning the war. Not a good time for the rest of the North if he survives, but there is a chance for a better future if he is taken out of the picture.
Once Geralt exits the warehouse, Philipa comes by and informs Geralt that their plan will not work so easily. She then gives Geralt Vizimir II’s (Radovid’s father) ring to make it more believable.
The next step after obtaining the ring is to meet with Radovid, whose ship is conveniently docked just outside the warehouse.
Luring out Radovid
Once you board Radovid’s ship, you must speak to the men on the boat and demand an audience with the King. After some discussion with Radovid, he agrees to follow Geralt to Philipa’s location.
There will be a series of dialogues to choose from in the conversation with Radovid, but the choices aren’t that important because they will always lead to the same conclusion.
Arriving at the chosen location, Radovid orders his men to close the bridge leading to the Temple Isle, blocking the way out. He then goes ahead and orders Geralt’s death. However, just as Geralt is about to get killed, Roche jumps in and saves him.
The ambush will start now, and a fight will break out. You will only be given a basic sword at the start, but kill a few more enemies and you will get your own equipment back.
Defeat Radovid’s men
The fight against Radovid’s men will be fairly easy because you will have your allies’ help. Sometime later, Radovid will try to flee, and Geralt and Roche chase him. You will encounter a few enemies during the pursuit.
Do note that there is a bug here in Reason of State that doesn’t let you interact with Radovid if you use the Axii sign during these fights.
Moreover, you will need to kill all the Redanian guards, especially the one standing in the corner, and if you miss out on killing him then the bug can also get triggered. You can easily spot this particular Redanian Soldier on the right end near a large pillar. He will be standing there during the entirety of your fight, so target him with a bomb that will provoke him to attack you.
You can kill him, and this way you will have fixed the Reason of State bug and won’t encounter it during your quest in The Witcher 3.
In the end, the mad king Radovid reaches a few locked doors and is cornered. One of the doors opens a bit later, revealing Philipa to be there. She then kills Radovid in an instant. The king is now dead, and the merriment can begin.
Decide the fate of Thaler, Roche, and Ves
With Radovid now dead, the group heads over to the theatre for a celebration. However, things take a turn over there.
Dijkstra comes forward with his own plan where he will become Chancellor of Redania now that Radovid is out of the way. He will wage the war against Nilfgaard and reunite the Northern Realms.
Dijkstra knows that Thaler and Roche wouldn’t let him do this, so planned accordingly and brought seven of his men to surround them and kill them. Geralt is now faced with a choice, let Djikstra live or Roche. This choice in Reason of State will determine who becomes the ruler of Redania at the end of The Witcher 3.
You can either choose to walk away and let Dijkstra handle Thaler, Ves, and Roche. If you choose this option, Dijkstra will become the next ruler of Redania. Note that his rule will be no different than Radovid in terms of living quality for the people, but the industries of the Continent will bloom.
You can also choose to kill Dijkstra and put an end to his plans. You might also encounter another Reason of State bug while choosing this dialogue choice. When you choose to fight with Vernon Roche against Dijkstra and his men, you will be able to take out his men, but Dijkstra will appear stuck on the stage, and due to this glitch, you won’t be able to inflict any damage on him.
You can fix the Dijkstra bug in the Reason of the State quest by going to the left side of the stage. There you will find a locked door, which will have some armor hanging on the right side. You will notice a wooden wall so jump over it.
You will find a big door on your left side, which will be unlocked so go through it and make your way as far as you can from this objective point. This will then force the cutscene after you have killed Dijkstra and also fix this bug in TW3.
In my opinion, the best ending choice for Reason of State in The Witcher 3 is to eliminate both Radovid and Djikstra. This way, Emhyr takes the throne, and eventually, Ciri can lead if she becomes the Empress of Nilfgaard.