Dota Underlords alliances list shows all the gains you can achieve by combining similar units in this new stand-alone game Auto Chess. Mastering the ability to connect units with the same classes is one of the most important abilities you need to develop in order to advance in the game.
Each character has at least two different Alliances, and if you combine several identical characters of the Alliance, you will receive a bonus for your minions. Each class requires a different number of heroes in combination to get a bonus. You will notice that there are vertical lines next to the alliance icon, you need to fill all the bubbles in one of these vertical lines to get the bonus.
Some Alliances require more units than others, it depends a lot on the number of heroes that make up this particular Alliance. A larger alliance, such as an Assassin, requires three minions in a vertical line. This means that you will need nine assassin heroes to get the full bonus for the class. Blood-Bound, however, only requires two units to receive a bonus, because there are only two units in this particular Alliance.