Ailing Kingdom Twisted Minds objective help needed

[Aprilwine]

There are 3 objectives and the 3rd is to win with 50% Health...for the life of me I cannot get this down. There is no % on health bar so how are we supposed to actually know when our health is at 50%? Also, if there is a trick to this please let me know...thanks in advance

EDIT: Figured it out! Since there is no way to pass a turn and you have to hit the mobs my only thought was to enter fight with very low level, non upgraded units. My Eddie is lv20 maxed for the area so this actually worked the first time. Maybe it was pure luck but got it done. Good luck out there

[Gonzo]

It's 50% or more. If you have a healer bring him and keep them healthy.