[Steam] Idling in the game again today

I got a new weapon for my mage and increased my attack power by about 80. I didn't get anything else, so I couldn't clear any more stages. Even after idling in this game for about 2 hours, it's not easy to clear stages starting from Nightmare. I was stuck at 3-5 when I last quit, and I couldn't get past it this time either. This is because I gave my priest Arcana-grade shoes last time, and they had a bonus stat for movement speed increase. So, I'm still using the priest skill I equipped to heal efficiently, which creates a healing zone, but now that movement speed is faster, the priest receives less healing and characters are leaving the healing zone. Also, since the archer and mage's damage has increased, monsters die quickly, causing issues with the priest's holding ability. I can't remove the Arcana shoes, nor can I reduce the archer and mage's damage. It seems like I can't clear 3-5 because I can't find a solution to these problems. I guess I could clear it by just mindlessly increasing my stats, but that would take too long, so I need to find a way to increase the priest's healing received.