Here is the early requirements relative to trust levels. The TL3 requirements were changes to less than 20,000 posts read. the precise number is elusive, but definitely more than 6.5K
Use a code line to post a URL as most users will be at “Trust Level 1” or less. Note that other Blizzard forum trust levels do not pass over into the Diablo forums. So for example, if you are trust level 3 in the World of Warcraft forums, you will not be trust level 3 here. Attempting to post a URL without wrapping it will result in an error.
Trust Levels
Trust levels are a participation system on the forums. The more you post, like, reply, read, and visit the forums, the more you work your way to a higher trust level. Increased Trust levels grant additional privileges. Everyone who is new starts off at Trust Level 0 but will quickly climb by reading and visiting the forums within their first few days.
TRUST LEVEL 0
Trust level 0 users cannot:
Flag posts
Post more than 3 topics
Post more than 10 replies
TRUST LEVEL 1
Get to trust level 1 by…
Entering at least 5 topics
Reading at least 30 posts
Spend a total of 10 minutes reading posts
Users at trust level 1 can…
Post unlimited topics and replies
Edit wiki posts (more on Wiki Posts Below)
Flag posts
TRUST LEVEL 2
Get to trust level 2 by…
Visiting at least 15 days, not sequentially
Casting at least 1 like
Receiving at least 1 like
Replying to at least 3 different topics
Entering at least 20 topics
Reading at least 100 posts
Spend a total of 60 minutes reading posts
Users at trust level 2 can…
Create links and video embeds to trusted websites like Blizzard websites, YouTube, or Twitch
Have an increased “like” count.
TRUST LEVEL 3
Get to trust level 3 by…
Must have visited at least 50% of last 100 days
Must have replied to at least 10 different topics
Of topics created in the last 100 days, must have viewed 500 topics
Of posts created in the last 100 days, must have read 20,000 posts (both starting posts and replies)
Must have received 20 likes, and given 30 likes.
Must not have received more than 5 spam or offensive flags (with unique posts and unique users for each, confirmed by a moderator)
Must not have been suspended (including forum suspensions or in-game account actions of any Blizzard game)
Trust Level 3 users can
Create Wiki Posts (more on that below)
Post animated gifs, images, compatible video embeds, and links to any website