Yes, this is copy + paste from my other thread. I'm not going to type it all over again.
According to the official rules, this is the ONLY rule for quest lockout in Hardcore:
"There is a level lockout to prevent characters from running quests too far over level. (Base level +4, or effective level on elite +2)."
However, when actually playing on Hardcore, no one seems to actually know what's going on with higher-level quest lockouts and challenges.
Some people insist you can only do challenges at the base level plus 4 (Meaning if a challenge's lowest difficulty is 5, you can do them at lvl 9 max or not at all, even if you try to step into a higher CR). Others say you can do a challenge whenever you want as long as you enter no higher than CR + 4 (So even if a challenge's lowest difficulty is 5, you can do it after lvl 9 by entering CR 6 or above).
The late teen quest lockout rules are an even bigger mess of rumors and conjecture. According to the official rules, you should be able to do a lvl 16 quest at 20, a lvl 17 quest at 21, etc. Keep in mind I'm NOT talking about Reaper here. I'm talking about N/H/E. However, from what I've heard, once you take lvl 20 in Hardcore, you're locked out of ALL heroic quests, including lvl 19 and 20 heroic quests like Dreaming Dark. However, it gets better! I've now heard you actually CAN enter heroic quests now so long as the level you're playing it on is over 20, meaning a lvl 19 quest on elite, but I don't know for sure.
What the heck guys?! I don't really care what rules you decide to make up, but abide by them! Make it clear in the official rules (Seriously, this would take five minutes for you guys to write in if you're too lazy to fix the coding) exactly when a character will be barred from entering challenges and heroic quests. Whether a character is going for Reaper xp or favor, a sudden lock on planned quests basically throws a wrench into everything.
/rant over
Now, a question for the community:
Can anyone verify from PERSONAL EXPERIENCE (not hearsay) on Hardcore Season 3 (NOT past seasons) what the state of these heroic lockouts is? If anyone with a lvl 20 character (haven't made it there yet) can take a bit of time to just push the "Enter" button on a lvl 16, 17, 18, 19, and 20 (heroic) quest, that will help me and I imagine many other people immensely. You don't have to complete it or anything. Just see if you can enter it.
On challenges: I took a lvl 10 character today to see what I could do. I went into Rushmore's Mansion: Behind the Door, Lava Caves: Circle of Power and Kobold Island: Kobold Chaos (all lvl 4-15 challenges) and got the same result in each: Not only was I able to enter the challenge on CR 6 (which is the lowest official rules say a lvl 10 should be able to enter), I was able to enter all three challenges on CR 4, 6 levels below me! As of this post, there appears to be no lockout at all on challenges, but experiences from other people to confirm this would be good.