There are five gold slots in the skeleton marked as "mana fixing or multicolor card that can be played as mono?". I'm not sure where that was discussed, but it does make sense. In the same way as Alara Reborn had a few cycles of cards that you could use even if you only drew one colour of mana (the Borderposts, the Sojourners, the Architects of Will cycle, the Valley Rannet cycle), if we're going to have 20 gold commons it'd be nice to make some of them usable even if you fail to draw both your colours.

Another Valley Rannet cycle of basic landcyclers is one option, but I'd like to explore some other possibilities. One such is some creatures with ETB abilities and Evoke. It's fun that this cycle could naturally have creature abilities for the non-evoke colour: This is a sorcery-speed Impulse with nothing nonblue about it, or a white-blue creature with the decidedly nonblue ability of first strike.

Good idea.

One drawback to this idea: It means Evoke is "one of our returning mechanics", and there aren't many spaces for those. Other possibilities for this slot are Senate Jurist and Gloomriding Warden.

Would colored Cycling make more sense? It would do a good job supporting Enlighten...

I'd also be pumped to see Evoke make a comeback, but I'd have to point out that Evoke is a bit complicated, and most modern sets would insist on having reminder text for Evoke on common cards. Since we couldn't sneak that many Evoke cards in, we'd probably end up with some very uninteresting evoke creatures in the end...

Coloured cycling is a definite idea. I think if we had it on gold cards we'd probably want it on monocoloured cards too, but I'm sure we could do that.

Would you be thinking "Cycling ", "Cycling ", or "Cycling "? The first would definitely evoke memories of the Glassdust Hulk cycle. In either of the first two cases, it'd be better than that cycle we might get people who literally couldn't cast the cards maindecking them in order to get instant-speed Enlighten triggers, which is kinda awesome.

If we went for more expensive cycling, or or more, then we could have cycle triggers as well, like Renewed Faith and Primal Boost. That'd make them feel more like they provided value when cycled even without an Enlighten trigger out.

I put forward an idea in Senate Jurist that I like. It's an evolution of cycling that hasn't been done before, so there's some bonus points there.