Well I learned something new, I thought ALL engrams were decoded at a set light point when they dropped. I must have missed that Luminous can grow with your LL for a week. Sweet great to know - thanks for the question OP.

First off, these are my personal opinions based off of what I've been able to come up with on my own. It seems to me, that the general consensus is that luminous engrams/powerful gear/whatever you want to call them, will, in fact, auto-decrypt upon weekly reset. However, for those in the same boat as me, you may not want this to happen. My theory is that it is always more beneficial to decrypt them right before the reset. My reasoning for this is that when the game automatically decrypts them, it is decrypting them at the same power/light level across the board. If you have more than two or three, it is better to manually decrypt them, so that you can use the first few to raise your power level as you go, so that by the time you get to the last one, it may be a few points higher. EXAMPLE: I was sitting at the soft cap (265) and had 5 different luminous engrams waiting for me to redeem. I slowly acquired them from the beginning of the game and had not redeemed them, so I literally watched them grow from low 220s all the way up to mid 270s. As of Monday right before the reset, i managed to luckily get a few VERY lucky drops. enough to push me past 265 (still without using my luminous engrams/powerful gear) so i was sitting at around 269, my luminous/powerful gear were all high 260s with an exotic in the mid 270s. I redeemed them slowly one by one, so my first engram increased my power level enough to push the next engram that was waiting up 1 power point, this didnt happen every time, because i got two of the same pieces (thanks bungie lol) BUT i waited on the exotic until i was done with all the others, i increased my light from the legendarys enough to be sitting around 274/275 power level. Once i decrypted the exotic and recieved a good weapon from cayde-6, I went up again. All that being said, at the time i posted this question, i was sitting at 265 wondering where the hell to go from here, and when I should decrypt my gear, now im at a comfrotable 277 (im a failry casual player) and still have the ratking, mida, and sturm all waiting to be redeemd in hopes that i can up my level enough to push them into the 300 range before redeeming them. Thanks for all the responses! Much appreciated! And also, we've got a clan, 13 very active members, all with mics, we use discord to constantly organize strikes and raids and we take pride in helping anyone who needs it. Come join our discord and party up sometime! >>>>>>> https://discord.gg/cRUxSd

I had 2 luminous engram and thought I had lost them at reset but then I noticed 2 high leveled pulse rifles in my inventory so I believe they automatically get decrypted.

Raising power level wouldnt matter, the rules for all engrams apply to those as well, when you comlpete the weekly they are considered dropped so you can raise its level

i still have a luminous engram waiting for me at the emissary. it didn't auto decrypt, but the milestone is still available from last week. will i be able to decrypt it come friday? i can't travel to the spire right now because trials is inactive

Not sure but I remember the Sunrise bounty from D1... I had a habit of completing this bounty but not turning it in. After reset I'd go to ZoVoLa and he'd say "you can only hold one of these" I'd turning it in, get my crap-roll Octomb's (en)Rager, trash it and miss out on that bounty for the week.

Auto decrypt at reset.

Please remember that a lot of the luminous engrams like the flashpoint, crucible call to arms etc. will get reset by Tuesday. So it makes sense to redeem them every week by Monday night at the latest. You get to grind for a new luminous engram starting every Tuesday. To answer your question about what happens to it, I've read somewhere on Reddit that it auto decrypts for you at reset.

It's best to get them before the reset because it resets your progress

I left one at Cayde last week and it disappeared on last weeks reset. No auto-decrypt that I could find. Just gone forever

Might be a good idea for everyone to check for any rewards from all vendors before every reset. ESPECIALLY CLAN REWARDS! [i]shutting down caps lock now.[/i]

I know some like the clan xp one resets each week. I got it last week and this week. So you may wanna turn that one in before reset so you can do it again.

100% they auto decrypt. I was waiting to use my first luminous until I was over 270 before last reset and the engram was gone Tuesday but I had a new powerful item in my inventory.

They get opened automatically you do not lose them, both my chest piece and legs i am currently equipping dropped from luminous engrams. How do i know this? Last week i forgot to open them before reset and when i got on Tuesday i had a bunch of legendary and exotics i didnt have before the reset. So yes they open automatically if you don't open them in time dont worry. I freaked out at first when i saw the Milestone reset but then saw my inventory and was relieved.

Yeah, open them now before they reset.