How to get Decay?

Same

You can't use remnant allies that are empire with a leader tag or a droid remnant. Essentially you can't use either Moff Gideons or Dark trooper on the team

I'm not, and still not getting it.

What team exactly are you using?

Take a Night Trooper into your team.

I’m getting 1 Decay per battle with Enoch, Death Trooper Peredia, Night Trooper, Stormtrooper and OG Death Trooper. I’ve tried it by taking out Stormy and Death and replaced with Tie Pilot and Scout and still nothing. 

You have to get killed without a crit. Then enoch lead saves you by applying decay and healing you upto 9 times. It's kind of like reverse endless ranks. So enoch unique zeta for 350% crit avoid would help. Voluntary vanguard to make your stormtrooper take hits to let enoch live would be good too.

I found having Enoch die got my ball rolling on a node with GG and wat.  My squad was 6-star Enoch, 6-star DT(P), r5 tie pilot, r5 storm trooper and r1 night trooper.  I’m swapping in scout next time to get some staggers. T took two battles and on auto and somehow I won the second battle for a star. 

Enoch, death trooper perdia, night trooper and scout trooper.  I have won 5 battles with them and I have not gotten it once.

I did this in 2 battles you don’t have to win I have all the named troopers from below at 3 stars with maybe gear 4 or 5 I lost twice and got decay bonus done with Enoch lead both zombie troopers death trooper and storm trooper