Your deck is missing a card.

Also, Riku is a very mana hungry deck so I'd up the ramp count to at least 8 sources. Putting so many taplands makes your deck slow, just skew your deck landbase to be more blue-green heavy and cut red sources as few of your cards need red, you can fetch the red sources out later.

Bump up your land count to 37 lands and then add around 8 sources of ramp. Maybe something like:

Thank you for the help. I've tweaked the list quite a bit. I'm really looking forward to getting this thing up and running soon.

Riku looks like such a fun commander. I might look at Kruphix, God of Horizons or Thought Vessel over Graceful Adept , despite that they can't be sac'd to Prime Speaker Vannifar , just to throw my opinion out there. Also, Mirrorpool lends some additional potential for great big plays; I use it in my Melek deck. It can be just win-more, in which case you might prefer a dual land, depending on how well your color fixing tends to play out, but it can also be exactly the extra value you want from a land card.

*edit: Kruphix can't be sac'd to fetch Purphoros , is what I meant to say.

I can see where the two are better than Graceful, and I may take your advice on Kruphix, but the reason I went with graceful is because I can outright clone her with no preface card, like mirror gallery, and if 5 or 6 of her hit the table, I'm more likely to have one or two survive a few turns.

Looking fun, any updates after you have tested it?

Trying to figure out what runs best in my playstyle. I've gotten it down to going off between tun 15 and 25 consistently, from where it started at 30+ turns. Testing out a build replacing the Signets with Talismans. But it's not going as well.