At the beginning of your next main phase, add an amount of equal to that spell's mana value
And while each card you draw after that still raises the odds of seeing Ob next, they wont raise the odds nearly as much as if your deck was built to 60 cards
This deck would cast Squandered Resources, sacrifice all lands to Natural Balance, then cast Cadaverous Bloom, and then pitch cards to generate mana and draw more cards
To make up for that, however, it also tacks on Toxic 1, allowing you to bring Poison counters into the game if your deck could take advantage of that
Conversely, if your key cards are all cheap, you can run a very lean, aggressive deck
There have been "miscut" booster packs, as well as 'double printed' boosters, and even boosters with a tape-like covering that have been found in booster boxes