The Chosen Ones

Suggestions are good, but you also need to decide what to do with the other difficulties. If we do all this for normal we need to look at hard and extreme and what effect it will have there too.
But yes normal is too similar to easy

What I meant is that the increases I mention can be progressive as difficulty gets harder. Like more and more armor for each monster as I proceed from easy to normal to hard to extreme and to ****