Another +1 wait for mana, as @ferg said, HA9 is good and faster while waiting and hoarding ETT for Ninja Event. I was paused HA10 and do HA9 about 8x, and gave me one Mana Dark and one Mana Yellow. And if you retrain, make sure you do not input blue crit, just in case…
The other HA is HA6 (stanby) for iron stock and troop feeder.
Wait…
You do not have any overload Crit troop, I was only retrain my 6th or 5th or 4th Crit troop.
But If I were you, I still doing HA9, just keep only one Crit is enough for a moment.