So I decided to test the amalgamation recipe, Mutagenic Essence. I had 24 legendary items to transmute: Luminous Powder Luminous Powder and Infusion of Scale Luminous Powder Luminous Powder Luminous Powder Luminous Powder Luminous Powder Luminous Powder Luminous Powder Luminous Powder Luminous Powder Infusion of Scale Luminous Powder Infusion of Scale Luminous Powder Luminous Powder Luminous Powder and Infusion of Scale Luminous Powder Luminous Powder Infusion of Scale Luminous Powder Luminous Powder Luminous Powder Luminous Powder I am sorry I am calling ******** on that Mutagenic Essence. I got 2 items at once only twice. The REST of the materials were a single mat only. Total from 24 legendary items: 21 powders, which is the lowest possible for a legendary item 5 Infusions.
My gut feeling is that some of the amalgamation recipes either a) don't work or b) the percentage bonus is so small it would be almost impossible to see any meaningful advantage from them.
The refining one doesn't seem to do much, either. I get right around 50% purified with it running or not. I "thought" 50% was the no-potion target. Last night I refined 157 rares, getting 79 slags (4 low q, 75 high q), 78 single rares, and 1 double rare (carbide, yay). Exactly 50/50. Potion, shmotion, if it's supposed to be getting me over 50%. Of course, as Hijinx says, if it's "+1 on the 1-1000 roll", we'll never be able to prove it, as players. We need the devs to give us the numbers. Which they won't, because then everyone who transmutes 25 things and gets 1 fewer mana than specified will be in here making threads like this one. T11 seems to have switched back to the "original" transmuting table, which was around "80% low reward, 19% high reward, 1% both rewards", IIRC. I suppose that's fair since we don't have double-white-slotted items anymore, and adorns are infinitely reusable once made, so we don't "need" the infusion-plus-multiple-powder-plus-multiple-fragment results this tier. So, in 24 attempts, you should expect 24x0.2 = 4.8 infusions and 24x0.81=19.44 powders. You're a tiny shade over that, but with a sample size of 24, you can't say squat about the effectiveness of these potions, other than "if it's supposed to be noticeable, it's too small."
I made 5 of the Mutagenic Essences early on and got about the same results as you did. I take all the legendary stuff I get from all my toons and dump it in a shared box. I take it out and mass transmute it all at the same time. Results using the Essence seemed worse then when not using it. I haven't made one of them to use since.
Would we expect Mutagenic's to have any benefit on Adepts? All our guildies drop (Adepts) in the scroll depot, and we once and a while mass mute them all. I could let them build up to, say 200, and try 100 with and 100 without the potion. *If* we would actually expect a difference with Adepts that is..
You should expect a difference based on the items description. Using it you should end up with more powders then fragments when you mute all your adepts. Where not using it you'd expect to get more fragments. But based on my experience you'll see no difference or get worse results using it.