Destiny: Cryptarch changes coming this week

Bungie will patch the Cryptarch in Destiny on Tuesday so that engrams will only decode at their level or higher. For example, blue/rare engrams will only decode to blue or purple/legendary, and purple engrams will never decode to blue. Rare engrams will also have a higher chance of decoding to legendary. However, Bungie warns in their dev notes that any legendary engrams you find now but wait to decode until after the update will automatically decode into rare, so get them decoded now and look for your legendaries later. 

Daily and weekly challenges will also include more chances for rare and legendary rewards, and ascendant materials now have legendary status.