I run roughly 5-8 roc strikes a night, I ALWAYS get at least 3 legendary engrams-althought I think ive come up with a way to influence the drops. They are almost always at the end of the strike when mission countdown starts. I have gotten 4 universal remotes and a suros the last 2 weeks, 2 ghorns, mida, dragons breath from legendary engrams, 3 ships, over 10 shaders (all dupes tho), tons of legendary snipers (all solar for some reason, 90 percent of my legendary drops are solar).