gistfile1.js

function extend(from, to){
	var x, r = Object.create(from);

	for(x in to)
		r[x] = to[x];
	return r;
}

function Mage(name) {
    this.name = name;
}
Mage.prototype = {
    cast: function(spell, can){
    	return can?
    		this.name + " cast " + spell :
    		"Nothing happens!";
    },

    meditate: function(){
        return "You start meditatin... zzz";
    }
};

function Apprentice(name) {
	Mage(name);
}
Apprentice.prototype = extend(Mage.prototype, {
	cast: function(spell, can){
		return Mage.prototype.cast.call(this, spell, can || Math.random() < 0.5);
	}
});

function Sorcerer(name) {
    Apprentice("Mighty " + name);
}
Sorcerer.prototype = extend(Apprentice.prototype, {
	cast: function(spell){
		return Apprentice.prototype.cast.call(this, spell, true);
	}
});