As far as I can see, there's no simple way to exclude the back faces of cards without excluding entire editions they appear in, or excluding their names one by one
Multicolour, Artifact, Land, White and Blue Cards Cards that Only Create Blood Tokens White only has one card that can create a Blood Token with Sigardas Imprisonment
This leads me to believe that Amethyst is the best Ink color in the game simply because its the only one that offers numerous ways to draw cards and cycle through your deck
There will be times where it is big for sure, but a two drop that you probably cant play on turn two isnt exactly ideal, and the upside is still just a large vanilla creature
You may play that card for as long as it remains exiled, and mana of any type can be spent to cast it
Vengeful Ancestor has a goad trigger for ETB and attack, which is great