By the way, it's treasures often tapped, not gold. Brainfarted so hard I forgot which is which lol.

Honestly I'd consider gold to be a definite color bend for WB, yet it fits the theme so well of a civilization which fell because of greed and avarice which only remnants are oligarch ghosts and skeletons. That sounds very Orzhov coded.

The current factions have

BR: Sacrifice matters, temporary power and wide boards
WU: Control, suppression, bonus for having non-mixed tribes
RG: Pump, landfall and pings (range theme)
WG: Anthems, populate
WB: reanimation, gold through extort

The last one is obviously the odd one out

I've attempted to design them around wedges/shards instead just to see if it could remedy this problem, but it muddles the design too much and has the same 4-1 split (although, funnily enough, the odd one out is not the same)