You're not the only one to have problems with it. From my side, I kinda expected people to die in the tutorial and restart it, but it seems like it's hard enough to make multiple people quit, so I've already started making a few changes. Such as a full heal at the start of the second phase.
It sounds like you pretty much understand how to beat the first phase. The full heal would probably have helped a lot.
Did you catch the bit of the tutorial where it says status effects have tooltips? If not, I can make it a bit more obvious that you're supposed to check the status effect on the card.
Also, the new character is friendly, maybe I can make that a bit clearer too.