Lairs
Lairs are a group activity in which each member has a path of decisions and battles, quite like a roguelike activity. You build a team of temtem according to tems you obtains during the lair, as well as equip gear and use items based on where your path leads you. A run can take anywhere from 30 minutes, up to over an hour - for example, in the above video, it lasted 47 minutes, which included some 7 minutes waiting for my team to finish their battles and obtain as many bonuses as possible.
At the end of the lair, if your team has managed to earn 18 mythical jewels, then, you are able to face the mythical tem Tyranak itself, which usually has 3 traits and 5 lives! Make sure to update your techniques as well as prepare enough items to ensure you can beat Tyranak and get your rewards!
Rewards
Once per week, you will get a mythical egg on your first victory. However, you may still do more lairs in that week to gain rewards which often include DNA Strands (for breeding), wish you well coins, Telomere Hacks, and quite rarely, Egg Technique Courses. You may even get multiple Telomere Hacks in one run (e.g. I got a Defence and Trait Swap Hack in one of the rewards). With these rewards, lairs have become the most meaningful end-game content to date.