Hearthpwn

Mistermath's Card Ratings for Voyage to the Sunken City:

3/10

The card is extremely bad in a vacuum, as normally, you don't want or need 0 mana cards in the late game when you're already at 10 mana, and the sole dredged card being reduced in cost by 3 mana is an effect worth 0 mana (see Illuminate). The only reason why this card isn't a 1/10 is because it has some theoretical potential to work with cards that dredge multiple times at once, or flip your deck upside-down, or - oh hi, Sir Finley, Sea Guide! Fancy seeing you here. Turns out, Sir Finley, Gorloc Ravager as a tutor, and From the Depths is a powerful enough tempo swing to put into control warrior as another tool for contesting against aggro, and is the sole reason why card is being rated a 3 and not a 1.

this fits into pirate warrior extremely well, most pirates are 5 mana or less

This is better than ramping. 15 mana for 3 and guarentee your next card costs 3 less.

Clunky. Won't work

too slow of a card, maybe dredge and draw would have seen play,

Weird card, really encourages running tons of dredge so you can benefit from all of the discounts.

A very interesting card.  It nets out mana neutral on the one card, and gives further bonus for later if you can get there.  A control tool.