I dont think hygn+desl without ptnm should be counted, because hygn+desl with and w/out ptn, are the same reaction in different ways. Also ive accidentally made sing via prot collisions, and its really not hard.
EDIT: I think all reactions are designed to NOT be too hard, still easily achievable, because if not, it wouldnt be as fun.
I think the PROT to AMTR reaction is too hard/underpowered right now, as even my Nearadia devices that create loads of SING from PROT rarely ever create AMTR, even with massive TUNG targets.
Not quite a reaction, but YEST reactors are stupidly difficult. The idea is to warm YEST to grow it, then burn part of the YEST without killing it. Since YEST is infinite, we'll have an infinite fuel source.
Use deserialization to control the exact temp.Then transport YEST using PIPE.
nobodyagain made a stupidly simple one, they arent hard if you dont overcomplicate them