RBA Reviews

Cthulhu 850 RBA and Kraken Tank

Cthulhu have already released a fantastic little Boro mod with their tiny AIO, and we got to play with their 850 RBA kit to go with it (or any other Boro device you might be using!)

Share on:

Fairly recently I treated myself to a Cthulhu AIO mod, I love the small form factor and there was a purple option, so it really was love at first sight. Sadly I had a bit of an issue with the paint finish, so I got in touch with Cthulhu to get things sorted out. I have to say that from a consumer’s point of view, they were absolutely fantastic, really friendly and super helpful. Everything got sorted out quickly and we ended up chatting, and they asked if I’d like to have a look at their 850 RBA for a review. Well that would be a great big yes please! If it was anywhere near as good as the AIO, then I was very keen to try it out.

Cthulhu 850 RBA family

First look and Packaging

The package arrived shortly after, and immediately there was a certain style to things before I had even opened the box. In my spare time (what little I have!) I am a bit of an audiophile, and the box the 850 RBA comes in reminded me of a good quality cartridge box, in fact it is very similar to my Hana EL box, a classy green textured effect affair with a posh looking gold logo in the middle. There is a cardboard sleeve which has a small description on it along with the authentication bits and bobs, I like this as it means the box itself can maintain that minimalist class thing going on.

Inside you will find a bit of paper showing the basic assembly and a link to Cthulhu for more information, a bag with spares and a set of seals in bright green if you want to liven the basic colour scheme up, as well as a hex key which you won’t want to lose as you will need it for the build deck, the 850 RBA positioned in the Kraken Tank, and a set of four airflow inserts. It is a nice package which is well presented.

Cthulhu 850 RBA contents

The Kraken Tank

First up, let’s look at the tank. If you are looking for a good quality tank for your Boro style device, the Kraken definitely worth a look as it is available separately and is fully compatible with other bridges. I very much prefer the two piece type tanks as it makes accessing your bridge or RBA so much easier, it can be a right fiddle in the ones with the sliding glass fronts and I am always up for anything that makes my life easier. It also has a convenient fill port at the top front of the tank for easy filling on the go.

So far, it looks like just another nice tank, but look at the underside and you will find an empty channel going towards the entrance hole for the RBA base. This brings plenty of air directed to the airflow system, and it works very well. I found whatever option I used (more on that later), the airflow felt smooth and there were no annoying whistles or whooshes.

Cthulhu 850 RBA airflow inlet

The quality was generally good all round with a decent level of fit and finish. Everything held together well, and the seals fitted perfectly. For the RRP, this is a really good option if you need a spare tank.

The 850 RBA

Now the real meat of this review, the 850 RBA itself. Looking round things before I got building, and the quality looked pretty good. There are a couple of areas which highlight that this is a mid-priced RBA though, for example the quality of the printed logo on the bell is a bit blurred, and the chimney felt loose but I will get on to that further in. But there was nothing that stood out as being worrisome. The machining is perfectly serviceable, everything basically fits well, and the deck looked straight forward.

Cthulhu 850 RBA parts

One of the features of the RBA is that it is aimed at restricted DTL to DTL vaping and they advertise that is has a “smaller domed chimney”, smaller than what, I am not sure though as it looked like a fairly generous dome to me! But I’m not complaining as I am quite happy to have a little extra headroom to fit my coils in. But this was the first sign that this RBA is a little confused as to what it is trying to be.

One thing I really love is what seems to be missing. There is no adapter for you to fix it to your chosen building platform. But when you look closely at the base, you will see some threading, yep, you can screw it directly in to a 510 without any extra bits to lose. Game changer! Combined with the easy anythime airflow changing, these make a very easy to adapt kit that you can tweak easily on the go.

Cthulhu 850 RBA airflow pin change

Building was easy thanks to the traditional clamp style, although be careful with those grub screws as they felt a little soft. If you over tighten things, I think it won’t take long to strip them and then they will be unusable. The clamp system does hold your wire very well though, and it also made wiggling the spare wire from the legs off nice and easy. There is enough space for a 2.5mm coil, but anything else is a bit tight. I tried a 3mm and there wasn’t much room for error. For DTL, I would have thought that there could be more space for more exotic coils, you really won’t be able to fit anything chunky in here.

Cthulhu 850 RBA build

It took me a couple of attempts to get my build right and I must admit I did end up watching a few YouTube reviews to see what they did (thanks Todd and Bogan!), but I didn’t really get on with either of their methods. I also have to admit that I took my photos before I hit the sweet spot, so take these more as a guide on what not to do. First up, I tried a regular coil with the legs coming under, and I went with Bogan’s longer wicks. It worked but the wick tufts looked ugly, and I also found the juice wasn’t wicking well. I got a few dry hits as the wick strangled as it came in through the juice ports.

Cthulhu 850 RBA wicking

Then I tried Todd’s wicking without having any wick coming out of the RBA, so basically cutting it to fit to the entrance of the juice ports. This worked better but the flavour was muted, and I just felt it could perform better. It was a serviceable vape, but nothing special.

So finally I went my own way and did something I hate doing normally, I went with an upside down coil. My logic for this was that the coil was seated too high with the previous methods, and this was causing blips in the wicking which were effecting the vape. Flipping it over meant the coil lined up much better with the juice ports. I also threaded the wick though the wicking holes just a bit to it was just outside sitting in the tank itself…bingo! Much better flavour, I’d go so far as to say this was great flavour. It also totally got rid on any dry hits and gave me a tasty, well saturated vape. Now I was quite impressed, this was turning in to a nice bit of kit.

Cthulhu 850 RBA priming

Once the coil and wicking was sorted out, it was time to play around with the airflow. This is another great addition with inserts that you screw in from the bottom so you don’t need to strip your build to mix things up. The included pins are 1.5mm, 2.0mm, 2.5mm, 3.2mm, and 3.8mm. There is also a cog that sits around the connector which you can turn to cover the airflow a bit. It is simple and serviceable but not the most accurate to use.

Cthulhu 850 RBA juice inlet

It was worth the time and effort it took to dial things in properly, the rewards were definitely worth it, and I ended up really liking it but not as a DTL vape. The large airflow options just didn’t work for me with the smaller coil diameter, it just wiped out the good flavour that it can produce. I found that it was at its happiest as a loose MTL RBA and would actually quite like the option to buy even tighter airflow adapters, a 1.0mm airflow option would be near perfect in my opinion.

Cthulhu 850 RBA airflow inserts

Now so far things have been mostly pretty positive, but there was one quite large annoyance, and that was the fit of the chimney to the dome. It is so loose that it made trying to take the base off with juice in the tank a bit of a messy nightmare. Sometimes things would come off cleanly, but more often than not, the chimney would separate too far up which meant that any e-liquid just dumped itself everywhere. For the sake of a thicker O-ring or a tighter tolerance, this seems like a glaring omission. It doesn’t affect the vape at all, but it would be a massive quality of life upgrade for those times when you want to change your wick without waiting for an empty tank.

Cthulhu 850 RBA wick tails

Final Thoughts

I love the Kraken tank, this is a really strong addition to any Boro collection, great quality with a couple of really good features. For the price, it is a bit of a steal. The 850 RBA is very good if you take the time to have a play and dial things in. It can be a very nice vape when you get things right, but don’t expect to get things perfect on your first build. Don’t get me wrong, it isn’t that complicated, I am more just highlighting that you will be well rewarded for taking your time. I still think it is a little unsure of what it is trying to be, and there are a few areas which could easily be improved (yes chimney, I’m looking at you!), but in the price range, this is a solid RBA.


  • Great tank
  • Innovative connection to your build deck
  • Easy to build
  • Good options for customisation
  • Secure clamps


  • That chimney
  • Slightly confused design, don’t expect pure DTL

Scores: 7.5/10 – small improvements could make the Cthulhu 850 RBA kit very special, but it is still well worth considering.

Cthulhu 850 RBA in Aio

Michelle (Purplefowler) avatar

When her usual forum closed, Michelle found herself in a brave new world full of excitement that something fresh and new was happening. A few days later she somehow found herself on the moderating team and is still not really sure how that happened. Even stranger, she slowly worked her way up to admin and now helps behind the scenes, liasing with vendors and coordinating social media but she can still be found making smutty comments on the forum. If all that wasn't enough, she also is a proud member of the Potv review team specialising in E-liquid reviews for the discerning vaper.

Join the discussion

RBA Reviews

Hellvape Fat Rabbit 2 RTA

Hellvape carry on their strong run with the Fat Rabbit 2 RTA

RBA Reviews

Thunderhead Creations Tauren Boro Tank

Decent vaping doesn't have to cost the earth as Thunderhead Creations prove with the new Tauren Boro tank

RBA Reviews

Hellvape Dead Rabbit Solo RTA

Looking for a new single coil RTA? Hellvape might have just the thing with their new Hellvape Dead Rabbit Solo RTA

RBA Reviews

Vapefly Alberich 2 RTA

Antony has been a fan of Vapefly products for a while, so he was delighted to get the chance to check out the new Vapefly Alberich II mtl RTA