Tower of Time

Most likely you will get it automatically as you progress through the game, since Swords is a pretty good skill. But if you use other skills, or want to speed up the process of obtaining. Then set the game difficulty to “History” and go to any test with portals. Wait for more enemies to gather there, then dash there and immediately use Swords. Most likely you will receive it on the first portal. Because the dash will take off 80 percent of the enemy’s health, and the swords will finish them all off.