Well this is what I have so far
Amethyst pillar x 19 (Tried and tested in like 50 games, if I use less I usually have problems with quanta)
Quantum pillar x 2 (Not sure about theese, but if I mutate my own creature I want to be able to use it's skill)
Maxwell's demon x 1 (Great in the right situation, but not so often so just one)
Abomination x 4
Purple dragon x 5
Dissipation field x 1
Mutation x 4 (used offensively in conjution with antimatter)
Antimatter x 4
Mark is entropy of course.
I just beat a guy in PvP with this deck, but I'm sure it can be improved.
Completly unupgraded.
Tactic: Get out the damage dealers fast but always save some quanta for mutate + antimatter on enemy creatures...
Edit: Just found the weakness of this deck, lost a PvP to a guy who used fractal and cockatrice, lots of small/medium creatures kills this deck (can't mutate/antimatter them all), it's really great against decks with heavy hitters though...
I can't think of a way to counter that with mono-entropy... Dissipation shield just couldn't take it even though I had a lot of amethyst pillars out...
Oh and I'm soon able to upgrade my first card for this deck, I guess a fallen elf would be the way to go? (Even though I don't have one right now)...
Anyway if you like to try mono-entropy out, this deck wins 29/30 against level 3's... Great fun and beginner farming for some electrum.