Goblin Game

[Karshtakavaar]

Now I'm trying to think of cards that grant alternate costs rather than having them, but I'm drawing a blank on appropriate ones for this list.
It could be a cool way to let any card have an additional "Weaker when you don't have fixing" mode. Sadly, so many are post-FIRE designs that are just way above rate, or let you repeatedly cast the same spell and break your carefully curated approach to card advantage.

It's a shame Jhoira hard requires blue - she was the one that inspired this line of thought. There's probably something in the Doctor Who UB stuff that's similar, but again, post-FIRE.
Oracle of Bones? Invoke Calamity? Spellbinder? Galvanoth? Mindclaw Shaman?

Edit: Treasure Keeper might be a cool Eggs enabler?

 

[gaytransmulldrifter]

Invoke Calamity is definitely an interesting callout. Right now I'm playing Mizzix's Mastery as a similar card and it has been a big crowd pleaser, could definitely see also including Invoke as a secondary version of that effect. I try not to include too many ways to "cheat" on off-color costs without drafting the proper fixing, but I like having a bit of it here and there. Coolest one of these in the cube besides mastery is probably Fires of Invention, folks stumble over drafting it most of the time because they misunderstand how many things it can do but when it comes together here it's so sick.

 

[TekLazar]

I feel like this might be the Exodia you are looking for

 

[gaytransmulldrifter]

Yeah I have thought about this card. It is a very cool dream although based on my drafts so far I think paying WUBRG is nearly impossible, so it would probably mostly just get played as a ramp target.