I just deleted 3 year 1 exotics so I could infuse year 2 legendaries. I know the grind. Running patrols, doing bounties and running strikes drop enough to keep you going. For those who may not know: Engrams seem to drop more on precision kills (enemies die faster and you save bullets... win, win, win). You can infuse Warlock armor with Hunter armor or Titan armor and vice versa for each character.