Boss unit is the enemy target that your spaceship squad needs to destroy.
Bosses will come in different waves; each following wave is stronger than the previous one. There are unlimited numbers of waves in Space Crypto.
A boss unit has three stats:

1. Hit Point (HP):

When a battle starts, a boss has a full HP. Then as the spaceship squad attacks the boss, its hit point is gradually deducted. One hit point is equal to one damage caused by a spaceship.

2. $SPE reward:

$SPE reward is given after you defeat a boss. The amount of $SPE reward varies according to the boss level.

3. Showtime:

Each battle will have a countdown clock called showtime. You have to defeat the boss within the given showtime. If you fail to do so, you will have to restart from the first Wave again.