Is it just me being unlucky or is the yellow verse the hardest to acquire? For the last 2 vault events this seems to be the case for me. Lots of other colours, just not yellow. Frustrating!
Most players have that one verse that is a bottleneck for them. For me it’s verse 4. That drummer just doesn’t like me 
I’ve been getting Baz (verse 4) in dark stone lvl 12 explore
Verse 4 (yellow) is my worst too - it’s my limiting factor.
Verse 1 (green) pops up most, I have at least 2x as many of those as any other color.
I wish I could trade with. My verse 1 is the lowest. My verse 2 is 55 more than verse 1.