Profitability of Colosus
From Fallen London Wiki
It unlocks permanent (so far) adition to your zee deck.
Each card has multiple options with various checks (Dangerous and Zeefaring are most common) and sometimes quality locked option (X of Innerant etc). Cards progress zailing as usual and most give 2 CP to related pyramidal quality. After getting said quality to 7 new storylet opens anywhere at zee ang you get Elemental Secret for one aditional actions. That brings final EPA to 312,5 / 29 = 10,78 rounded up.