The pity thresholds
Rare at 6 rolls, Super Rare at 12 rolls, Uber Rare at 30 rolls. Once you hit a threshold, the pity drop is guaranteed - and it is guaranteed to be a unit you do not already own from that banner pool.
Worst-case Brick cost
Standard banner: 30 rolls x 100 Bricks = 3,000 Bricks per missing Uber. Premium banner: 30 rolls x 200 Bricks = 6,000 Bricks. Acquire the full missing roster before pulling blindly.
Uberfest math
Uberfest doubles the baseline Uber Rare rate from 5% to 10%. The pity ceiling does not change, but the expected value drops dramatically because random pulls hit Uber Rare twice as often.
Cross-banner pity
As of the current patch, pity counters reset between banners. Plan to use your Bricks within a single banner rotation rather than spreading across multiple.