Been playing a lot of Grixis recently.  Fable of the Mirror-Breaker // Reflection of Kiki-Jiki is such a strong card, and the removal/draw from black and blue are just really good.  Tried a full control version in an SCQ qualifier and got run over by white weenie and midrange: there just wasn't board presence.  It did beat other control decks I faced though.  You can view that list here:  Grixis Control SCQ, I just expected control to be the predominant decks and it wasn't for me.  So back the drawing board with this!

Kaito was too hard to protect against weenie decks, and would maybe get me a card but was more often than not cycling.  He got removed and Expressive Iteration got added.  To get that to cast turn three invoke got removed so mana could be more skewed towards red/blue.

Invoke Despair is a brutal card, and wins a lot of control matchups, but against midrange/aggro it needs to fire turn 5 to be effective, and that just doesnt happen often enough in Grixis.  Goldspan Dragon does fire turn five when you need him to.  He's always good in every matchup, and allows Dragon's Fire to be used as effective sideboard removal vs Reidane and Adeline, or other matchups where you need four damage.

Reckoner Bankbuster is amazing vs control, and with Trespasser turn 3 can be crewed offensively and defensively while providing draw.  Often you block AND draw, which is just crushing.

There is a The Kami War // O-Kagachi Made Manifest in the deck!  There's lots of treasure generation in the deck, so against control matchups this will fire more often than not, and it's triggers are pretty brutal.  Still testing this, but it seems pretty solid.

Hidetsugu, Devouring Chaos is another card I'm testing, and it's worked well when there's stuff on the board.  He generates card draw and damage, is a decent sized body, and can use your tokens to scry away cards to set his ability up the following turn.  

Hidetsugu Consumes All // Vessel of the All-Consuming wrecks token and graveyard decks, and is a great Kiki-Jiki target as a creature with trample.  I love this card.

The sideboard has enough creature hate to turn you into a creature killing machine for the two predominant creature colors right now(white/green), and has options vs. Draw/Go decks to help push your creatures through and protect them from board clears.  This can be tweaked obviously for matchups you're seeing a lot of.  Tatsunari, Toad Rider is an honorable mention, and something I'm gonna try out: maybe pull the Burn Down and Negate for a couple copies of him to be more aggressive vs control/midrange.

All in all, it's a solid and fun deck to play.  Enjoy!