Stopping Marchenko

M16: Stopping Marchenko is the 16th main mission in Deus Ex: Mankind Divided, and one of the last missions (depending if you did M17: Protecting the Future) first. Adam Jensen must stop Marchenko from detonating bombs that will kill hundreds of people, but at the cost of the UN delegates lives and letting the Human Restoration Act pass.

Achievements

 * He's [Not] Dead, Jim
 * Laputan Machine
 * Spokes in Two Wheels

Starting the Mission
This mission initiates after completing M15: Securing the Convention Centre by meeting Jim Miller in the catering area. If you did M12: The Heist and got the Orchid antidote, you can use it to save Jim Miller or, if you do not think you will make it to the delegates in time, save it for them. Alternatively, this mission will also initiate if you triggered an alarm in the convention hall. In this case, you can still find Miller in the catering area to save him using the Orchid antidote, but only if you do so before fighting Marchenko.

If you met with Miller, you are given a choice of either confronting Marchenko or instead proceed with M17: Protecting the Future to save the delegates. You may proceed either way.

Stop Marchenko Before He Blows Up the Towers
Contrary to what Marchenko says, he will not immediately blow up the towers.
 * If you decided to save the delegates first (by completing M17: Protecting the Future), you will have 10 minutes to get from the VIP room to the exhibition hall before Marchenko detonates the bombs. The easiest way to reach the exhibition hall is to use the hidden door in the conference room. The hidden door is part of the green monitors behind the mounted camera.

The timer for Marchenko's detonation of the bombs will trigger only upon completion of M17: Protecting the Future. Thus, there are no time constraints if you have not yet entered the VIP room with the delegates inside.
 * Otherwise, if you wish to fight Marchenko before saving the delegates, simply make your way to the exhibition hall.

Once you arrive at the exhibition hall, a cutscene will play. If you do not have the killswitch or chose not to use it, you will then fight Marchenko.
 * If you did M11: Confronting the Bomb-Maker and got Allison Staněk to give you the signal jammer, you can use it to prevent Marchenko from detonating the bombs, if he hasn't detonated them already.
 * If you got Damocles' Sword (Marchenko's killswitch), which can be found in one of the rooms in the catering hallway, you can use it during the prompt (or anytime during the fight with him). Please note that using the killswitch voids the Pacifist achievement.

An easy way to defeat Marchenko is to use an electric shock to stun him (such as the stun gun) and quickly proceed with a takedown. If using the stun gun, make sure you are in stealth, otherwise Marchenko will activate his TITAN aug, preventing the shock. Another method is to make a couple EMP mines and lure him in. When they go off, you can then run over and do a non-lethal takedown.

You may also exit the fight and save the delegates. Right after the cutcene, make your way up the stairs to where the turret is to find a switch underneath the table (near the mines) that will open a back entrance to the delegates. Follow the arrows to the executive lounge and enter. If you were fast enough, you will be able to save them. You can then head back through the hidden door (it is part of the green monitors behind the mounted camera) to finish the fight.

If you defeat Marchenko but have not save the delegates yet, use the secret door described above to quickly get to them. If you are fast enough, you will be able to save them as well.

Alternative Objective: Defeat Marchenko
If you saved the delegates first and then took longer than 10 minutes to reach the exhibition hall, Marchenko will then detonate the bombs, regardless if you have the signal jammer or not. The actual detonation scene does not occur until you reach into the exhibition hall. Afterwards, defeat Marchenko to complete the mission and proceed to the ending.

Aftermath
If you complete this mission last, Jensen tells MacReady that "it's over," and steps toward the window of the exhibition hall. The game will then cut to the ending and you can see how your choices play out in your conversation with Alex and on the news.