Yeah, there's definitely something we're missing, but I think we can safely rule out the following:
- No specific villain or environment. The Twitter post from page 1 has Voss at WMB, several other unlocks have been Ambuscade in Insula Primalis.
- No specific team size. We've had several unlocks with three-, four-, and five-hero teams.
- No specific teammates, unless it's an "either X or Y must be on the team" situation. The only overlap between PseudonymTweetr's team here (AZ, Omni-U, CC, PWAA, and Grandpa) and akamai's team here (Dark Visionary, RC Wraith, TLT, and AZ) is AZ himself.
- AZ does not need to be in a specific spot in the lineup, as shown by the screenshots in the previous point.
- DLC content is not otherwise required, per willgallant's post in the Steam thread here. (Granted, he does have Grandpa and TLT via the Unlock Variant button, but we've also had posts using standard Legacy and/or standard or Super-Sci Tachyon.)
- Thermal Shockwave and Cryo Chamber do not need to be in play, per willgallant's log here.
- Coolant Blast does not need to be in play, per serge's log here.
- Focused Apertures is not required, per NyxFSSD's post in the Steam thread here.
- No AZ One-Shots are required, per my unlock.
- The order of AZ damaging targets and healing himself doesn't matter. Nathaniel241 healed before dealing damage, I did the opposite order.
- A "setup" loss to Chokepoint is not required, per hynju, Yoshi348, and myself. In my case I haven't played a single game against Chokepoint since she was added to the video game.