I can't honestly call this deck "Simplicity" anymore, because it's grown in complexity, with harder to acquire cards...so I now call it..."The One-Handed Clap".
Basically, all I did was take my 3.0 deck, trim down some multiple copies of some cards (all fell to the sideboard) and added the planeswalkers, Temple Bell and Mind Over Matter...yes, I am aware of the infinite combo possibilities of those last two cards, and have used that in games already. With the Elixir getting me my milled and cast spells over and over (and over, and over) again, I found I didn't need extra copies of several spells...the Unsummon/Counterspell one-two punch is more than enough to remove serious creature threats, BUT, if I do play someone with artifact, enchantment or planeswalker threats, Boomerang can easily be swapped in for a few Unsummon spells.
I added two Profane Memento's because there were life threats against me, they pretty much ensure long life, since my opponents will be milling and discarding a lot of creatures, and sometimes in bunches.
I rarely use planeswalkers in serious decks, but I found that it is VERY hard to damage them once I get the ball rolling milling, unsummoning and countering, so getting to their hyper-mill/draw abilities isn't that hard. But they are still there mostly to amuse me...and they have a side-function as well...the longer the game is drawn out, the more likely I am to win, if my opponents focus on attacking THEM instead of me, so much the better...if they die..."oh, how ever will I get them back???"...but seriously, they aren't necessary at all, they are purely superfluous though that is useful in and of itself.
The deck is SUPER lazy...I mean, there are no activated abilities, save the simple tapping of the Temple Bell...so the hardest part of playing the deck, is remembering all the stuff that triggers automatically...
...each player mills X cards where X = the cards in their hand (Dreamborn Muse)
...opponent mills 3 cards when I play a land (for each Hedron Crab I have)
...each player draws an extra card on their draw phase (for each Howling Mine)
...gain a life for every creature that goes to an opponent's grave from anywhere (Profane Memento)
...opponents mill two cards whenever they cast a spell (Memory Erosion)
IMO, that's a lot to keep tabs on, but at least I don't have to tap anything to make it happen, which leaves me plenty of chances to use my instants!
6/2/19: I recently picked up a Font of Mythos card for the explicit reason to add it to this deck. I dropped one of the Elixirs to the sideboard to make room for it, not that it really matters one way or the other.
Offer to give your opponent as much life as they want. Double it even. This deck is entirely incapable of taking an opponent to 0 life, so whether they start with 20 or 40 or 1,000,0000...it really makes no difference. The challenge is, can you deplete your opponent/s library/ies before they drop you to zero life.
IDEALLY (in multiplayer) you don't want to hit the ground with too many mill cards early, you WANT to get defensive creatures in play first...just to protect your butt. In head-to-head play, it makes no difference, start milling them early with Hedron Crabs.
For the most part, the deck plays very smoothly, once your base defense is set, use Unsummon to get rid of potentially dangerous creatures, Counterspell & Mana Leak any threats (though don't worry about piddly things like life gain).
Howling Mines will get everyone drawing fast and furiously, once you get any of your automatic defenses in place (Dreamborn Muse, Memory Erosion, Hedron Crabs, the planeswalkers), drop a Traumatize as soon as possible (to do the most damage)...recycle your graveyard with Elixir of Immortality as often as needed as either life gain (to keep you alive) or to reshuffle those valuable instants, or lost permanents back to be used again. Rinse, repeat.
If you manage to get the Temple Bell-Mind Over Matter infinite combo rolling, it's game over...just make sure you have an Elixir ready to use! For those who don't know the combo: MoM is an enchantment that lets you discard a card to tap or untap a creature, land or artifact...in this case, you'll be using it to untap Temple Bell, an artifact that you tap to make everyone draw a card...the Bell gives you a card, MoM discards a card to untap the Bell...but all the other players are continuing to deplete their already diminished libraries and are slowly filling their hands one card at a time. Even if you are forced to shut the combo down because your own library is nearly depleted, if the other players start their turn with 15-25 cards in their hand and Dreamborn Muse is in play...end of game.
The deck is ridiculously low cost, if it wasn't for Mind Over Matter and the planeswalkers, every card cost 4 or less mana, with most costing 1 or 2. The key to the deck is Elixir of Immortality. That little gem lets you recycle those low cost instants back into your library to be used again and again and again. In concert with the Howling Mines and Font of Mythos and Temple Bell...filling your hand back up won't be a problem.