PSA: There's an optimal way to use the special blood consumables when buying certain Vampire abilities *minor spoilers*

Once you're a bit into the game, you'll likely have run into at least on blood vial containing boyar blood. Consuming one of these unlocks their special skill. The thing is, any sample past the first gives you a free level in that skill without using a timeslot or skill points. Obviously this means you don't want to manually buy more tiers than needed since that would "waste" this very powerful resource. Therefore, the best thing to do is save any extra instances of boyar blood until levels 3 or 4 of the skill. This can save a decent number of skill points and time slots.

For example, there are 3 Ambrus blood samples in the game, one from draining the man himself and two in vials from quests. Let's look at three different examples of maxing out Scarlet Shield.

1. Unlock, then max out normally. That first level is free, so we're looking at 6 skill points and 4 time slots. Ouch.
2. Unlock, then wait until all your blood samples are gone to max out. Only spending 3 points and 2 time slots for that last level. Still not great.
3. Unlock, buy tier two, then consume the other samples. Only spending 1 SP and 1 time slot!

As far as I know, Brencis and Xanthe have 2 "samples" in the game, whereas Bakir and Ambrus have 3. So the former two should see you unlock, buy two more tiers manually, then top off with the other sample. Bakir and Ambrus only need one manually bought tier, then other free sources get you the rest of the way there.