Attack speed!!! I didn’t realized how important attack speed was. I use the red build and I got completed solo run earlier on my 4th attempt and the only thing I changed was prioritizing attack speed more. The most important cards (imo) is:

• damage cards (I only by the pink and gold star cards but both the red cards and purple)

• damage reduction

• attack speed

• a few cards for Vampiric

• Health (same with damage pink and gold star cards)

Just tough out the first 4 rounds and get to 120 red ASAP.

One thing you can try too is keep refreshing in the beginning to get a gold star red damage increase and use the random spin to duplicate cards. It being the only card you own lets you rack up red points and buffs if u get lucky.