Originally Posted by kringley

Huh. So I guess there's a limit on how effective attack down can be? Maybe swap in a raid boss attack up girl and see if that gets you further? I can't really test it out myself.

No. It's much more likely the turn limit was reached. 100 turns/squad if I'm not mistaken.

There was a bug wherein the boss from one event (Gentian) didn't attack at all that a single unleveled 2* could survive for many turns!

The turn cap is not exclusive to raid boss fights. It's also enforced on maps, including but not limited to those with loops (like the coin daily).