This is the current incarnation of my Thassa Commander deck. Originally I had it set up with a lot of land auras to mess with my opponents lands, but I found that strategy to be a bit lacking considering it didn't really hinder my opponents in any meaningful way. I changed it up with a bunch of spells that mess with creatures instead, because making my opponent's commander do nothing all game tickles me just so.
The reason I picked Thassa, God of the Sea is because for a whopping 3 mana she's a 5/5 indestructible that can give anything I control avoidance and she can fix my draw every turn. The only real problem I've had with the deck is having enough devotion to bring her online, but I've been shoring that up as I go. With all the 2 and 3 drop permanents in the deck it's honestly not too hard to get her swinging and often times I'm holding counter magic or I've got things otherwise protected when someone decides to drop a board wipe so I've never really had an issue in keeping her on once she's on.
My current strategy is to get Thassa out as quickly as possible, bring her online, stack up auras, a few creatures, enchantments, and equipment, and swing for a bunch of unblockable damage. I've got a decent collection of counter magic to keep boardwipes off of me and I've found this deck can actually push mid game pretty hard in a 4 player pod and 1v1 she puts a lot of pressure on my opponent to the point that I'm usually getting a turn 6-7 kill, especially against decks that require time to set up. Being able to scry off of Thassa every turn really helps as well. I'm currently looking at ways to set up the deck so that I have alternate win conditions that don't involve combat damage, or at least don't rely on commander damage beyond Blighted Agent beats or stealing something with Dominating Licid or Vedalken Shackles. I usually end up at least surviving to be one of the last few players (usually I end up playing 6+ players at the table at my LGS) even if I don't win in the end, but at this juncture I'm unsure if it's personal skill, the deck itself, luck, or my opponents making mistakes with their actions or their deck building procedures.
I'll come back to this when I have an idea of the direction I want to head with it next. I'm looking for alternate win conditions that I can pull off without having to completely remake the deck in order to get them out consistently.
Making updates!
Turns out I've actually won more games with combat damage from Blighted Agent than with Thassa.
I dropped Commit / Memory, Propaganda, Shimmer, and War Tax and added in Coldsteel Heart, Everflowing Chalice, Guardian Idol, and I'm going to try out Tidespout Tyrant to see what kind of shenanigans I can get up to with that (the unlimited mana combos I could generate with Sol Ring and any of the cheaper spells in the deck make me a bit more than giddy). The deck's main win con is combat damage, but I'm starting to look at some alternate win cons that avoid that, or that make it so my opponents don't have anything to stop me from swinging with impunity. I would rather not turtle if I don't have to and since I don't have access to enough propaganda effects in mono-blue to make it worth my while I've decided to put in more mana rocks to speed up my tempo. Shimmer doesn't do enough when I get it out and Commit / Memory has its uses, but I don't see it as being as useful as it could be if I were running a different style of deck.
I may also up my land count to 33-34. I'm still getting flood more than screw thanks to Thassa fixing my draws, but those games where I get flood often times I can loot those extra lands away with stuff like Frontline Sage or Looter il-Kor.
