This article covers the fourth boss encounter in Bomb Squad.
In order to get to fight this boss for the first time, you need to complete all 5 levels of the fourth level cluster. You also have to go through a narrow mine field and deactivate a gas chamber before getting to fight this boss.
Killing this boss will unlock the fifth level cluster, with portals.
Doctor Reaper is the most difficult boss encounter in the game. This is due to the amount of awareness and swiftness required to defeat this boss. Before entering the doctor’s laboratory, you must have mastered the game. Not only should you know how to avoid bad items (plagues), you should be able to play with them. Because you will most probably have to eat some even if you are a perfect avoider.
When the fight starts, three plagues will spawn in random locations on the ground every 2.5 seconds. Considering the de-spawn timer which is slower than this, it can be overwhelming at times. You cannot exit the room as it heals the boss. Doctor Reaper will walk around the lair as he scatters the plagues.
You can immediately notice that the room is divided into four partitions. Inside each partition there is a gas-chamber machine. This suggests that you might be in great trouble. Because gas chambers don’t take long to kill you once triggered. The truth is, they are going to be triggered soon enough. Each 120 seconds (2 minutes) he turns on one of the gas chambers. It is NOT random. The pattern is always the same. Each gas-chamber machine covers one partition. Walking into that partition when the machine is working takes your health very fast. So you have to plan ahead. Once the fourth gas chamber is active, the fight should be done.
The fact that Doctor Reaper walks around a circuit around the lair looks like Lieutenant Chase. So, intuitively you should use almost the same technique. But here you also have the plagues and gas chambers. Plagues should not always be avoided. You must learn to adjust your brain to the changes the plagues impose very quickly. You simply won’t have time to avoid/blow all plagues on the way. The only plagues that should be avoided are those that paralyse you, such as Stun.
It takes a few runs to learn the mechanics, and some others to be able to defeat this boss. But defeating this boss is quite an achievement.
As this boss constantly spread plague on the ground, it automatically suggests that he is good with diseases! So this explains the term doctor. But he is also an evil doctor, as he does no good with his talent. His plagues and gas chambers are extremely deadly. So he is Doctor Reaper!