So I doubt I'm the only person insane enough to notice that the wording on the special part of Spelldrinker is a little ambiguous.
You temporarily add a 3rd-rank spell to your spell repertoire, as determined by the type of creature whose blood you just drank (see table below). If the creature has more than one of the listed traits, choose one and gain the appropriate spell. If the granted spell is not on your chosen tradition’s list, you cast the spell as though it was from your chosen tradition. The spell is removed from your spell repertoire after 24 hours, the next time you use Spelldrinker, or when you next make your daily preparations, whichever comes first.
Special If you have Surging Blood Magic, you can add the spell at 6th rank. If you have Exultant Blood Magic, you can add the spell at 8th rank.
Combine that with my own special brand of brain problems
Prerequisites: expert in Crafting; living creature, ability to cast 6th-level or higher spells from spell slots, completed ritual to become a lich and crafted a soul cage
So with that said and acknowledging that this might disappear with an errata just by me posting about it. (Paizo pls don't) Is there a reason a 12th level bloodrager with Spelldrinker and Surging Blood Magic couldn't preform the ritual to become a lich? Even if it's only for 24 hours, this would be a really cool (deranged) way to make a barbarian lich. Something I've always wanted to do just because you really really shouldn't even consider it as a valid option.
That doesn't give you any additional spell slots, just additional spells in your repertoire.
Exactly.
Rule citation for that:
Though you gain them at the same rate, your spell slots and the spells in your spell repertoire are separate. If a feat or other ability adds a spell to your spell repertoire, it wouldn't give you another spell slot or vice versa.
But once you do have some 6th level spell slots from Bloodrager, go for it. Barbarian Lich is completely on the table.