I love doing wacky and interesting deck building challenges (particularly for EDH) so around 2 months ago while chatting with some friends at my LGS I came up with a plan - every week for 6 weeks I would build a new EDH deck starting with colourless and adding a new colour each time (think the evolution of Omnath) until ending up with a full 5 colour deck.
I really liked the idea but soon realized that it wasn't much of a challenge, so I tweaked it a little deciding that the added colour would always be the one resulting in the "worst" colour combination and that I would always use a Commander I had never used before and that I would try to build in interesting themes wherever possible. After some discussion the colour order arrived at was this -
Colourless -> Mono White -> (+Red) Boros -> (+Black) Mardu
-> (+Green) WBRG -> (+Blue) Rainbow
Week 1 (Traxos Colourless)
Building a colourless EDH deck was an idea that i'd often played around with but never actually put together so I was super happy that this challenge gave me the extra motivation to do it. I was pleasantly surprised by how well the deck ended up playing, it felt viable even in a field of colour heavy opponents. My favorite part of the deck was Golden Guardian (a dual faced card from Ixalan block) which I'd always wanted too mess around with but had never found a good home for.
Week 2 (mono white Mangara 2.0)
For week 2 I went with mono white Mangara. Mono white is near universally considered the worst option in EDH and indeed I did feel that it was (somehow) down powered from even the colourless deck. I went from a pretty straight forward pillow fort strategy with a heavy enchantment theme. The deck did have Heliod and Teshar combos in it but with no tutoring I never pulled either combo off (I did lose a game with Heliod + Walking Ballista in hand though). My favorite part of the deck was Cartographer's Hawk (a commander pre-con card) which I managed to get out early one game and provided some nice ramp parity.
Week 3 (Boros Firesong&Sunspeaker)
For week 3 I went with Boros, Boros was traditionally by far the worst 2 colour combo for EDH (mainly due to the lack of good card advantage) but recently has seen a real uptick with commanders like Feather and Winota. I went with Firesong & Sunspeaker which is also a powerful Boros option (damage based board wipes and massive lifegain) not because of the power level but because Minotaurs are one of my top 5 favorite tribes and i'd never had a chance to use them. In addition the deck had a strong equipment theme and used Sunforger (an amazing piece of equipment that any Boros deck should consider running). I avoided infinite combos (even though with Godo it would have been an easy addition). The deck went well being a player in all the games (which more than winning is my main goal for EDH). My favorite part of the deck was probably the Brash Taunter, I've always liked Stuffy Doll and Taunter is a better version of the card (especially for EDH).
Week 4 (Mardu Tariel)
For week 4 I ran Mardu, choosing Black over Green as the next "worst" colour is a bit controversial but I hold that Mardu is worse than Naya or Jeskai for EDH even if Black is arguably as strong or stronger than Green (Blue is always King though ;) ). I chose Tariel because it's one of the original commander deck Commanders that I had never played with. As the options were now a lot stronger to mix things up I decided to go all out with the theme and built a creature-less deck that aimed to win only with Tariel or with creatures stolen from my opponents graveyards. The deck played wonderfully, being in a competitive position in both games. My favorite part of the deck unfortunately never got into play - it's Lethal Vapors (an Onslaught Block Black enchantment that destroys all creatures entering the battlefield and that can be destroyed in exchange for a player skipping their next turn), i've always liked the card and I hopefully can make better use of it in some future EDH decks.
Week 5 (WBRG Saskia)
For week 5 I went with WBRG and Saskia, earlier this year I ended up buying the International Women's Day Secret Lair (mainly for the Captain Sisay which is my One True Commander ;) ) and I got a copy of Saskia with it. Saskia is a very aggressive commander and I wanted to find a way to downpower the deck without making it unplayable. The idea I came up with was to make the deck (barring lands) 100% female, every non-land card has a woman front and center of the artwork. This made for a unique deck building experience, usually I can just go through my collection by colour pulling out interesting/useful cards but this time around I had to individually evaluate each card to see if the characters were male or female first. The deck was still very solid and far prettier than it would otherwise have been ;) My favorite part of the deck is Betrayal of Fortune (a red sorcery from Mirrodin block which allows you to look at an opponents hand and play a copy of an instant/sorcery you find) it's always been a favorite card of mine with a unique affect (plus the .... well endowed artwork made it one of the 1st things I thought of after deciding on the concept).
Week 6 (Rainbow Tazri 2.0)
For the final week I went with Rainbow Tazri, I decided to go all in on the party theme and too make the deck a bit more of a challenge I decided to run Jegantha as a companion (restriction the deck to never doubling up on the same mana symbol in a card). The deck went surprisingly well (for a deck which was 1/3 standard legal and had a number of mediocre commons) managing to even win one of my games. My favorite part of the deck was the fact that the changeling instants (Crib Swap and Nameless Inversion) were legal targets for Tazri's ability.
Overall thoughts
The experience was fun but exhausting, I like being adaptable with my EDH decks and having to hold back on my ideas because I had a set 6 week plan was difficult for me. I will also say that with the right cards and strategies any colour combination (even the "worst ones") provided to be fully viable. The only deck of the whole experiment that felt underpowered was the mono White one and even that was mainly because I opted out of powerful options like tutors.
Next Week
Next week I am planning to play a fully pauper EDH deck (uncommon commander and 99 commons, for more info - https://mtg.gamepedia.com/Pauper_Commander) I plan on playing an artifact heavy UB Rona deck (both because it's an interesting Legend I haven't used and because it leads to many groan worthy 'Rona puns).