OK after a bit of research (grinding heroic strikes) if you use 1 coin just before a ultra encounter you should get an exotic drop after every 5 to 7 strikes. But I must warn you don't be too disappointed you will get an awful lot of dupicate items. I have 3 invectives 3 telso fusion rifles 5 crest of alfa Lupi. Thanks for all the advice ppl. Back off to grind for a zarlo supercell joy 😐