I also have a Captain Sisay deck, so I thought I'd offer my advice real quick.

Mox Opal is pretty huge for the Paradox Engine combo turn. I strongly recommend adding it in as Sisay can tutor it after your first untap and let you generate N + 1 mana, helping you get closer to your goal of casting every legendary in one turn in the event you only have one dork or something, which happens (my list runs more than even yours does and I run into this from time to time lol).

I recommend Inventors' Fair, Azusa, Lost but Seeking (lets you play a new land on your combo turn, allowing you to get both Miren and Fair even if you played a land earlier in the turn), and Blasting Station. Don't worry about using Mindslaver to win and draw things out when you could infinitely do damage with Bow of Nylea, Station, and any legendary creature. Inventor's Fair's ability is reasonably easy to use, as with Opal, Paradox Engine, and Bow of Nylea (all of which are easily obtained on the combo turn using just Sisay), you can satisfy its ability, grab Blasting Station, and then kill every opponent by sacrificing Anafenza or something, bottoming it with Bow, and then tutoring it back to hand with Sisay and re-casting it, untapping, and then using Station again until everyone is dead.

You could drop Mindslaver to fit in Blasting Station, any land to fit in Inventor's Fair, and I honestly don't think Karametra is good in this deck so she could be removed fairly easily to fit in Azusa, who would help on your combo turn (Karametra brings the lands in tapped so she's only useful during a long, grindy game, in which case she's a poor backup plan and win-more in almost every case she'd be good).

I am also a huge fan of Umbral Mantle with Selvala, Heart of the Wilds as they produce infinite mana and, ergo, infinite untaps, which means if your Paradox Engine gets exiled or something you still have a very solid route to win the game. Sisay can get you both cards even if Paradox Engine is gone which can be valuable.

mazrimtaim I realize your comment was very long ago but just wanted to let you know that you cant play Fist of Suns in anything but a five color EDH deck because its color identity is all five colors.

OP why not play Yomiji, Who Bars the Way to do he mindslaver combo much more easily than your way of constantly discarding an eldrazi?

I may build this. seems very cool. +1 from me. I was looking over what changes i was gonna make and I saw "updated 9 min ago" so i was kinda excited to see what your thoughts are on this deck.

Awesome deck man. I've been trying out a Mardu Legends list with Queen Marchesa at the helm, but Sisay's tutoring is really cool!