I don't think your EM deck is too good. Adrenaline'd vamps, or decks like yours just that without cockatrices and with Adrenaline will most likely work way better.
I'm by no means an expert of level 3 EM grinding because I always use full-damage rush decks myself, but I'm willing to bet that what I used is much better than Adrenaline'd Vampires. Have you actually tried that deck? It sucks.
Without any buffs, those 2/2 Vampires are pretty much useless and will get owned by any creature control out there. Opponent plays an unupped Otyugh? Gratz, you just lost the game.
Problem with decks like that is that you basically need two cards to make one creature which makes them even more vulnerable to creature control, and also makes it more luck dependent.
Im enjoying using Essences AI3 EM Darkness deck (http://elementscommunity.org/forum/index.php/topic,11412.0.html). Even unupped (how Im using it until I can upgrade everything) it works really well.
I haven't used that same exact deck, but to me it looks very slow. The unupped version I mean. Also without any instant healing or not much defense, I don't think it will get that many EM's. Having a second shield might help with that.
I think the main advantage of the deck I used compared to these suggested here, is that my deck has Heals which you can use to give yourself full HP before you finish the opponent. Without instant heals like that, you will have less EM's because if your opponent has low HP, he will die before you get full HP.
The deck I used in phase 5 is probably the King of unupped Elemental Masteries but I will reveal it later.