Ooh that'll be a busy Race if it's not obtainable another way...
Anyways yeah, you want to get a lot of towers done and get high scores on them if you are playing manually. So anything that increases your score, so like Brutalities or Friendships are how you want to end each fight. Also do Mercies. Lengthier towers will give lots of points, but do smaller ones too to stack on in quicker ways too..
Some folks just have AI grind, which will give lower tower scores but they automate it over time so yah.