I want there to be a mana-fixing self-Theorizing card. Not sure that this quite hits the mark. You could do a turn one Theorize into turn two one-cost cantrip that fires off this spell. It's a simple and fun high point. As-is, this plays like a strictly better Cultivate, so might want to tune this elsewise. as a Theorize cost is fun, and I think it has design space. Maybe ?

I like

Theorize One Other Card

 

 C 

Sorcery

Choose and discard a card from hand. If you do, draw two cards. If the chosen card is an Instant card, Sorcery card, or card with an Omen, Theorize it instead of discarding it. (Exile the Theorized card. Whenever you cast another Instant or Sorcery spell, you may cast Instant and Sorceries spells from Theorized cards you own, and those spells cost less to cast)

Smaller version of

Theorize Two Other Cards

 

 C 

Sorcery

Choose up to two cards in your hand that have an Instant and/or Sorcery. Theorize those cards, then draw that many cards plus one. (Exile those cards. Whenever you cast another Instant or Sorcery spell, you may cast Theorized Instants and Sorcery spells, and those spells cost less to cast)

It's different and better than a Tormenting Voice. You discard on resolution rather than cast; you can cast it without another card to cantrip; you get to keep the card you Theorized rather than it being discarded. It does require a card that fits the criteria, and you cannot discard a land this way. Hmm, what if we changed the wording a bit...

This is a Tormenting Voice style card that utilizes the Theorize mechanic. It provides a lot more card advantage than the usual, because you can still cast the Instants/Sorceries that you Theorized. In effect if you Theorize two cards, this reads;

• Get to cast two of your cards later at a discount, and draw three cards

Given that, this either needs to be fairly pricey to cast, or should only theorize one card at a time.

Trying to think of "combination" Theorize cards. This would improve the damage of a burn effect. However, I'm not a fan of making people figure out how damage increasers plus trample works... I wanted this to be green because, "your stuff hits opponents harder" makes sense as a green effect.

Can counter any instant or sorcery spell, putting them back. This counters any number of target spells, so that you can put back someone's entire Theorize stack. They get to keep the spells, so it's not so bad! They'll need another instant or sorcery to trigger it to get it back, though.

This is meant to be a card that can return to your hand to fuel the "discard a creature card" effects. I like the idea of activated abilities that cost less based on how much brawlin' you've done this turn.

Not really sure what else to attach to this creature, or how to cost it... giving it "can't block" lines up with lots of return-y creatures, and Trample is in all three associated colors.

I really liked the idea of a faction's mechanic being "discard a creature card, draw a card, do a thing". Trying to figure out what "do a thing" is able to be. Haste seems like an obvious starting point, since it's present in all three colors.

I wonder how to word this in a way that enables it to target something... I explicitly want the "draw a card" effect to resolve, even if the chosen creature dies.

", then choose up to one target creature you control. That creature gains haste until end of turn."

Here's another shot at primary secondary common. How does this feel?

Cat is primary in Green and White, Spirit is also in those colors. Probably still needs some representation of Red, so we're tossing in Berserker.

Convoke shows up in red sometimes, but is primary in green and white. Haste shows up in green, so maybe it's not the best representation of red-ness. Vigilance is absent in red and present in green/white, so it brings this in to something that could only be at least green/white... maybe.

Probably need to think of something more red-aligned than haste.

This was originally meant to be part of the primary color with hybrid color common cycle, but I wanted to record this idea.

There are some Red Cats and Spirits, but Green and White get many more of these.

Red gets to rummage. This tries to tie it to the G/W identity by making the rummage require a Creature card, then making a small creature token. It's not a super-complicated design, and it feels like it can be elegant enough to be effective in draft.

Doesn't fit the common cycle's concept theme of only using straightforward existing mechanics. But this kind of card makes me feel like I'm understanding the faction concept a little better.