Some further thoughts:

Ninja Mudras don't necessarily need all 3 button presses to work, and I don't know if you want that same idea here. The drinks used straight up are buffs on yourself, but if you use a single-target heal, the Mix will affect a single target. Using an AoE heal will make the Mix affect all allies in range. However, using a damaging spell could make the Mix a debuff that affects a target, and likewise with an AoE damage spell turning the Mix into an AoE debuff on all enemies nearby the initial target. This still keeps it similar to the Ninja Mudra idea, but changes it enough so that's it's not a direct copy.

I was thinking Power Salves would make Regens, Magic Salves make Shields, and Speed Salves make buffs.

You could make the Fang items the basic spells (Fire Fang is single target, Thunder Fang is Multi-target, and Blizzard Fang is instant-cast), though I'm not sure how Mixes would affect the offensive spells. Maybe Strong+Fang just increases the damage, Speed turns them into a DoT, Magic makes a Debuff?

I know this will draw heavy comparisons to the other healing Jobs we currently have, but it doesn't seem like they want to make a job that does something other than regens and shields. I'm not sure if they should be able to mix into each other, and if so, if the effects should stack. Maybe another cooldown will allow multi-Drink mixing to get out multiple effects on the next Mix action. (Call it Distill or something, I dunno)