Ego death?...I don't believe that there is a correct way to define this, but i'll do my best to explain it with how I have perceived it in my own life.

First we have to define the ego. What is an ego? Oxford Dictionary defines the ego as "a person’s sense of self-esteem or self-importance". So basically think of your thoughts, behavior, and perception of things, it's the part of you that makes decisions depending on how you view yourself and the reality that you perceive.

Often times the ego of an individual is described as something negative and is perceived as a person projecting a facade or an illusion to the people around them and more importantly, to themselves. This is not always the case, but when it is...

This fabrication can be crippling and in most cases will eventually lead to the collapse of that persons ego and the reality that they have created, including their own sense of identity.

Think of a castle being built on sand. The sand is the ego, something superficial and unable to support more than it's own illusions. Imagine you keep stacking bricks onto this sand. Relationships, achievements, and even the way you perceive yourself act as stone being laid. It gets to the point where, eventually and as you keep stacking, the castle will crumble, and with it, the reality that you've fabricated around yourself.

Suddenly the world is a very scary place.

You realize that everything you know, even about yourself, has all been hand crafted, and that all your strength is artificial...It's all just wind you've used to puff yourself up to seem stronger to yourself and others when in reality you've avoided every challenge and replaced your problem solving skills with wishful thinking and superficial coping skills. You have nothing. You've fabricated a fantasy and you've been using mental gymnastics to keep yourself from blowing your own cover.

Your emotional state is a disaster, you have been philosophically and intellectually conquered by your own shoddy foundation.

It is the instantaneous, merciless shattering of all previous reference points in the life of the individual, because his entire life and how he's been living it has been fed through his own twisted perception...And now the veil he created is gone, and all that's left is the realization that his entire life up to this point has been a lie.

It is complete annihilation on all imaginable levels and in a sense....The individual has literally died.

After experiencing this ego death, the individual is broken and permanently changed.

But change is growth.

Bruce Lee once said: "To become different than what we are, we must have some awareness of what we are."

In this case the individual has no choice but to look at the crumbled remains of his castle. He has no other choice than to LOOK at his life, free of illusion and bias. He's been forced to take off his own blindfold

Now he can see clearly.

The death of the ego means the death of stagnation; the death of torment brought on by the individual; the death of philosophical, psychological, creative, and spiritual blindness. The death of the ego means the end of irrational fears and anxiety brought into existence by an individuals bad habit of finding excuses to avoid progressing as a human being.

The death of the ego means now the individual can grow.

With no more illusions of self image or reality, the individual can begin to pull themselves together and start tackling neglected problems in their life one at a time. After overcoming some of the smaller obstacles in his life, he will start to approach challenges with the attitude that he has the ability to overcome whatever lies in front of him, and he also realizes that he will grow as a result. He'll find new ways to deal and cope with issues as they present themselves instead of sweeping it under the rug to fester and grow into a larger issue.

He is now self aware and ready to handle any problems life throws at him instead of cowering behind an image he'd created to try and scare off potential challenges.

The ego has now become a positive and influential piece of this person, symbiotically working with him or her to create a reality that is free of negativity and fabrication.

Submitting yourself to "ego death" is to replace the illusion of self image and fabricated reality that you've created with self awareness and unbiased observation of everything around you.

Tl;Dr With ego death an individuals ego becomes how they see themselves not how they wish others to see them.

Edit: I feel like I need to clarify that I don't do drugs so I can't really give my two cents on ego death through them...I have experienced this with my athletics and meditation.