Summary:
With this patch, we address some widely-discussed concerns with how Engrams are earned and claimed. Strikes have become more rewarding, and the rewards gained from them are more predictable. Also affected is the rotation of maps that appear in the Crucible.

Cryptarch
Legendary (purple) engrams will always produce a Legendary quality item or higher
Note: Legendary engrams that exist in your inventory will change to Rare quality items when the patch is applied. However, decoding these engrams will still produce the same results as before
Rare (blue) engrams will always produce a Rare quality item or higher
Chance for Legendary gear increased
Materials: Ascendant Shards and Ascendant Energy promoted to Legendary quality (from Rare quality)

Rewards
Rare (Blue) and Legendary (Purple) Engram drops added to the potential rewards for:
Vanguard: Tiger Strike Playlist
Daily Heroic Missions (first time per day)
Weekly Heroic Missions (first time per week)
Known issues
When selecting a higher difficulty for daily missions, XP Bonus not show in the reward display
You will still get the XP bonus, you just won't see it in the UI

Crucible
Reduced time limit on Bastion and First Light in Control and Clash from 15 to 12 minutes, bringing them in line with non-vehicle maps in those playlists
Lowered weighting on Bastion and First Light in Control and Clash so they appear less often in those playlists