Barbarian mixes
Barbarian mixes are the same as regular potions, but the only difference is they hold 2 doses instead of 4. The positive part of it is you only need 2 sips, and each sip can restore 6 health. The only minor negative is that it acts as food to interrupt your attack cycle. It also acts as food when sipped. You will need to wait for an additional tick before swinging again.
Where and How To Yse Barbarian Mixes
If you plan to make it yourself rather than buy it at GE, you need to complete barbarian training up to the herblore section. Two criteria that I think might be good are taking small and avoidable damage and in a situation where 4 doses of potion aren’t needed. Some potential slayer tasks where barbarian mixes are worth using are Drakes, Wyrms, Zygomites, Suqah, Nechryael, Hydra, Basilisks knight, and Dagannoth.
Drake is a good example. Instead of taking one dose of strength, attack, and defense potion, I will swap them with one dose of barbarian mixes that gives extra 18 healing per inventory, thus saving some slots.
Bossing like Vorkath is another great example. Here we can get an extended super anti-fire at the bank pre-pot and put an extended super anti-fire mix in my inventory, and I will get extra 12 health per trip. The rest of the inventory is sharks.
Some other examples are Ourania Altar inside the waterbirth dungeon. In this situation, you need to run a lot and get small and unavoidable damage. Instead of taking a health and stamina potion, you can bring a stamina mix to get both health and stamina at the same time.
If you are an iron man get rowan caviar to mix the herbs rather than farming all by yourself, and you can do herblore training by creating barbarian mixes. It is super slow and annoying, but it’s worth it to have tons of emergency options. These potions also have flipping potential. You can get a much cheaper mix than a regular potion depending on the market value.
Conclusion
Is it worth it? In my opinion, it depends on the situation. If you do not have to bring many items, you can use these mixes for extra health if you are on a task. But if you get a lot of loot then it’s probably not a good idea to bring these mixes because it can add up to the extra inventory slots. So it depends on your task.