Union Raid is available for guilds that reached at least level 3 and each Raid Season will last for 7 days. For now we don't know how often the mode will become available, but the first season will start on the 27th January 2023.
Overall, if you played Princess Connect, you will feel at home, because the Union Raid is a direct copy of the mode. For some, this will be a blessing, but for others, a curse. While casual players will be able to smack the bosses and get some rewards, for those that want to reach the highest ranks things will look much complicated.
As mentioned earlier, to access the Union Raid you need to be a part of a Union that's at least level 3. Then the Union Raid tile visible on the Union screen will become available to you - but keep in mind that you won't be able to enter it till the season starts.
After entering the Union Raid you will be welcomed by the screen above that shows the current round, the current boss and how many attempts you have left for this day. All of that is visible on the image above.
Which bosses you fight depends on the season.
Once your guild defeats all 5 bosses within a round, you will advance to the next one and again fight Obelisk first. Though keep in mind that the difficulty of the battles will also increase as with each stage, the bosses gain more stats.
We created a dedicated page for each boss where you can find its stats (per stage) and also videos showing sample battles (as the bosses already appeared in the story).
You only get 3 chances a day to attack the bosses and you have to build 3 different teams to do that - if you use Modernia in the first battle, you won't be able to use her in the remaining ones. This will force you be smart about the characters you use against each boss, because for sure some will shine in different teams and against a different boss.
Also, since the difficulty of the bosses will drastically increase with each round, the weaker members of the Union should attack in the first rounds, so the strongest members can deal as much damage possible against the stronger bosses.
The main reward in Union Raids are Union Chips that you can spend in the Union Shop to buy spare bodies for characters obtainable thought Liberation mode and Batteries used to upgrade your Cubes.
You can obtain Union Chips for killing one of the bosses and based on the rank your Union achieved after the season. You can check the Season rewards here: