Yeah, I know... but please wait a sec!
I've got a tip for you.
Since the player life system is the same as "Roguelike" type games (*), this game might be hard before you notice an important tip.
"You can RETREAT any time without penalty."
If you feel you may lose, you don't have to wait till the very end. Simply retreat from the battle, refill the life point (if possible), then, come back with different strategies as many times as desired.
(*) Basically lose everything when a game session is over.