Sometimes the third eye brick can take quite a while to show up. I will tend to make bricko oysters to fight in-run. It takes about 8 summons (on average) to get the three eye bricks, that said, it can swing wildly. If you assume 8 summons, then you've got 3 eye bricks + 3*2 + 5*3 = 17 regular bricks. So you could fight 3 bricko bats, or you just do ~3 more summons, and fight 3 bricko oysters. Huzzah.
Just depends. I will use bats if things go regularly, oozes if the summons are lucky, and oysters if things go a little longer than average (which, they often do). That's if i'm using brickos though.