Mix this little freebie up with Diffuser and have some fun!  Frohmage from Ohm Force! 
 
https://www.ohmforce.com/ViewProduct.do?p=Frohmage
 
This plug-in is a multi-band resonant filter: it is built using a resonant low-pass filter running in parallel with multiple band-pass filters. These are then followed by a distortion stage.
 
Start with a sample or a synth sound and go from there! 

oops wrong thread.

That Biotek thingy is nice, haven't seen it before.
 
I've played with frohmage a while ago, again no very good results. After all digging it comes down to not having one great Reverb but a ton of different ones. Same goes for instruments.
 
I've already added Diffuser to my collection, wish it was bug free.
 
Prices are nuts. So I figured I'd rather buy one-for-all like UVI Falcon and maybe Phalanx, cause I need a sampler anyway. Again, prices are freaking NUTS, 349€ for Falcon wtf? Everyone's doing this sales crap, just double the price for the rich and the crazy. Then "sell" at regular price. I can see a regular price of 179€ for Falcon, sales price maybe 149€ - which by the way was about the introduction price 3 years ago.
 
400€ here, 300€ there, you could spend like 10.000€ and still lack a ton of plugs you want.
 
Anyway, back to topic, for now my workflow is to record traditional digital synth to audio, load em into Iris 2 and mix / mangle them together, which isn't too bad for either workflow (relatively quick) or results.

I took a look at that Iris 2 thingy, now kinda wished I hadn't, LOL!  It's on sale for $126 right now.  Already blown my budget for this month, so will have a few new features to add to my Synthmaster V3 wish list!  Need to go post over on KV331's forum!
 
Iris 2 is a sample based synthesizer with a killer workflow for building sounds from scratch quickly.
 
I really like how Iris allows spectral filtering of multiple wave samples, in both dimensions of time and frequency.  Take a little part of one sample and blend it with part of another, and so on.
 
The graphic display really shows what is happening, and you can see the waves in a timeline type view like a DAW.
 
By comparison, Biotek is also a sample based synthesizer, but it's strength seems to be using multiple LFOs and modulation routing to achieve the movement within the sounds.  The x-y pad in the main page display allows realtime morphing between different sounds, so it is very organic sounding.  It also ships with mostly wave samples of nature sounds, so you have plenty of ambient source material to tweak.
 
But for the same money, I would probably pick Iris 2.  It looks like it would be more productive.  It is also very unique with the spectral filtering, and the workflow is very intuitive and visual.  If using the LFOs and mod matrix is what gets you going, maybe Biotek is for you, but this is what keeps me from digging deeper into Synthmaster.  It can be done, but it takes some work ...

I got Iris 2 at around the same price. Although all you said is true, it's also a bit limited. There're these unique and extremely powerful options you mentioned, on the other hand I feel some very basic stuff is missing.
 
There're more LFOs and Envelopes than you could possibly map in a useful manner to the handful of manipulation options. Little unbalanced here.
 
Also if you want to use a send effect per part the global fx can't be used anymore.
 
The master filter section can only be added globally and not per part. I think that's the biggest issue. At first I thought it wouldn't make sense to have another frequency filter on top of the spectral filtering (also frequency based), but it makes sense if they existed and you could animate them via LFO.
 
Still no regrets on that buy, neither on Iris 2 nor on Neutron I got as Crossgrade from Iris 2 for around 80€. What a timesaver. I love that, simplicity and stuff that just works so I can be creative and not be stuck on technical stuff.
(I was really lucky to find it at the time, I think it was a leftover from a previous sale. Pluginboutique listed the Crossgrade at the same price as the full version.)
 
EDIT: Been talking away.. What I wanted to share about Iris is that you have to make a little shift in mindset. A good part of creating the patch happens outside Iris. And it's not always as simple as mashing 4 random samples from your personal library together.

occide
 And it's not always as simple as mashing 4 random samples from your personal library together.

Happy accidents! 

Happy little clouds :)
 
Not sure how I overlooked this for so long:
http://glitchmachines.com/downloads/hysteresis/
 
And of course:
http://glitchmachines.com/downloads/fracture/
 
For free that makes an excellent combo with Iris 2.

Getting back to very organic sounds or what sounds like them, the granulars are excellent at this. The more organic the original sample is before Granite or Mangle gets to work then the more organic and very complex does the produced pad sound result. Granite and The Mangle do not sound alike and although they are both granulars they do different things resulting in the different sounds.  Granite has enormous modulation options (of parameters) and the means to create the modulations with your own self expression and record and playback those moves accurately. That is a pretty cool thing to watch. 
 
Imagine making sounds with Granite and then importing into Mangle and going further. Or import a Granite or Mangle sound into Iris 2 and manipulate from there.  Increases the possibilities.
 
Making very closeup and quality recordings of things very natural, instruments but also many day to day sounds is rich food for all three synths mentioned here to get to work on.

I considered buying Glitchmachines Polygon today - it's pretty cheap atm and comes with an extra sample pack. Yawn - sample pack... but the Glitchmachines sample packs are excellent for this cause. They have two packs for free I tried out today. These you actually can throw into Iris as they are and get a cool pad sound.
 
What holds me back is that Polygon is monophonic, and I cant find a single example on the web of a pad created by Polygon. Maybe because it's monophonic.  Anyone can help me out here?
 
Just as another "mangler" for preparing a patch for Iris I don't want it, got already plenty of options.
 
40 bucks here, 20 bucks there.. it adds up, too. In the end I could have bought Falcon...

Just a quick note: I tried the Serum Demo now, so I had a 1:1 comparison with my attempts in Iris 2.
 
My personal opinion in regards to the topic:

• Iris pads sound a notch better than Serum
• Serum got some great FX like Delay and Reverb, but if you listen to the dry signal Serum still put on pants one leg at a time like most other synths
• Even with the custom wavetables option and the point that Serum has become a defacto-standard with loads of free and commercial patches available I think $189 is too much for Serum. It clearly has dated a bit (yeah I know, the Demo is not the most recent version, but I also watched the videos.) For me personally around $120 would be a fair price.

If you want to make ambient like me you can easily go with Iris and couple of samples, you won't miss out on anything in comparison to Serum. Still if you don't care that much about the price Serum will be a great synth for ambient, standalone or side-by-side with Iris 2 (or other synths).