Mizzix, Eye of the Buyback Storm (EDH / Commander)

Mizzix is my personal favorite commander to pilot. The unique elements of Mizzix are the ability to transform cards from over-costed to silly-cheap and the explosive nature of the experience counter accumulation. Mizzix also has a few interesting interactions beyond making cards cheaper. Mizzix allows for the reduction to apply to alternative and additional costs for cards like Capsize, Cyclonic Rift, and Increasing Confusion. X-cost spells will always increase the number of experience counters by paying the colored cost of the spell and applying the reduction to the generic X-cost. For example, you have 2 experience counters and want to play Fireball, cast it for 2 on X. This counts as a 3 converted mana cost spell, increasing the experience counter count to 3, and you only paid (R). This works when starting on any number of counters, from 0 to 100.

This specific build has a few building restrictions for the sake of fun. While I love blue, I feel it's a bit off-balanced since it is the only color in the pie that can consistently prevent the effects of instants, sorceries, and enter-the-battlefield abilities through counterspells, so none of those. There are also no extra turn spells. (Honestly, your turns will take long enough once you get Mizzix to stay for more than a turn.) Mizzix has a tendency of getting banned from casual playgroups and turning every extra turn spell into a Time Walk isn't going to help its case. From the pilot-perspective, the excitement of this specific commander is the near immediate switch from nothing-going-on to biggest threat at the table and extra turns takes away from that feeling for me.

The goal in the early game is to get as many experience counters as quickly as possible. Once the counter total hits 5, things should start to get fun. At that point, here are the interactions/combos available:

1. Almost all instant and sorceries in the deck cost 1-2 mana, just the colored mana.
   (The main goal of the deck)

2. All of the Buyback costs are free.
   (The best of the Buyback cards for this deck is certainly Reiterate. It allows for all instant/sorcery spells from anyone to be copied by you for the low, low price of (R) (R).)

3. Reiterate + Reality Spasm/Turnabout/Mana Geyser/Brass's Bounty = Infinite mana.
   (For those who are not familiar with continuously copying a singular spell, read this. Step 1: Respond to the instant/sorcery spell you want to copy while it is on the stack with Reiterate and target the spell. Reiterate is put on top of the stack, in front of the desired spell. Step 2: Allow Reiterate to resolve. This puts a clone of the spell on the stack on top of the original spell. Step 3: Allow the clone spell to resolve. In the case of the example above, this allows you to untap lands, untap lands, make red mana, and create treasures, respectively. Step 4: Repeat Step 1. As long as you are making more than 2 mana with the copied spell, you can cast Reiterate as many times as you want, creating infinite mana.)

4. Mystic Retrieval + Runic Repetition = Unending graveyard returns
   (The roundabout Reiterate. To start the loop, Mystic Retrieval is in your graveyard and Runic Repetition is in your hand. Begin by using Flashback on Mystic Retrieval to return any instant/sorcery in your graveyard to your hand. Next cast Runic Repetition on Mystic Retrieval to return it to your hand. Finish by using Mystic Retrieval on Runic Repetition, returning it to your hand and finishing the loop. The end result is one instant/sorcery for a minimum cost of (U)(U)(R).)

5. Blistercoil Weird/Gelectrode + Paradise Mantle + Whispers of the Muse/Searing Touch = "Unlimited POWER!"
   (A pretty straightforward combo after the last two. Tap the equipped creature for mana then cast the 1 mana spell with Buyback. This untaps the creature, which can then be tapped for mana to repeat the combo.)

6. Runaway Steam-Kin + Searing Touch = Death by pings
   (Basically #5 again. Use (R)(R)(R) to cast Searing Touch 3 times, which puts 3 counters on Runaway Steam-Kin. Remove the 3 counters from the Steam-Kin to make (R)(R)(R) and repeat until everyone is poked out of the game.)

7. Aetherflux Reservoir = A load of life and an instant-speed kill switch for anyone at the table.
   (Just cast 17 spells in a turn with this is in play. Once the 17th spell is cast, you will have gained 153 life, enough to kill 3 players at starting life totals and leaving you 3 life higher from where you started)

8. Thousand-Year Storm = A test of your math and stack skills, along with your opponents' patience.
   (The game-ending enchantment, similar to a Bonus Round + multiple Reiterate. Get the most from your mana as this gives all of your instants/sorceries "Storm". This will often result in table-wide scoops if you ever untap with this enchantment in play.)

A few extra tips:

Mizzix is often hate-boarded in playgroups familiar with this build. Sometimes, the best counter strategy is to wait a few turns before casting it for the first time. If you play it once you have 6 or 7 mana sources, you'll be able to cast a few instants with the extra mana to start generating the experience counters. This gives Mizzix immediate value if you ever need to recast it.

Petals of Insight is a pseudo-Buyback spell, just choose to not take the cards and Petals returns to your hand. This helps build experience counters, search through your deck and can be used to build a higher storm count.

The first 3 cards that should be searched with Firemind's Foresight should be Searing Touch, Reality Spasm, and Reiterate for those who are looking to end the game.

Use Long-Term Plans to tutor for non-instant/sorcery cards, ideally any artifact or enchantment. They're harder to find in the deck, cards like Uncovered Clues can't draw them, and they are well worth playing before the spells start flying. The safest choice is to tutor Chromatic Lantern, because it helps ramp and, most importantly, color corrects.

Don't be afraid to use Increasing Confusion on yourself. Instants and sorceries milled are basically in your hand once the Mystic Retrieval/Runic Repetition combo is assembled. Runic Repetition can also return an exiled Increasing Confusion to be used again, so you can use the Flashback on yourself as well. Learn from the Past is also in the deck to return the permanent spells to the deck and dodge graveyard hate.

And with that, good luck and enjoy!