Exile everything and profit while doing it.  This is officially a Mythic tier deck that I climbed with over the course of a week of casual play.  I made it to Diamond within 2 days at a very high win rate but slowed down considerably while grinding to Mythic.  This deck is very fun to play with a lot of options for dealing with your opponent.  It is also honest to a fault, with very low amounts of instants (since in general you want to exile on your own turn).  Also as a side effect of your card draw engine, you get to watch Reanimator decks cry.  Struggles against monoblack midrange/discard due to sacrifice effects; and if you can't counter their discard/sac with hand attack you might not be able to get your card draw engine online; but if you do get it going you'll stomp them.  Also struggles against Dimir Toxic as you will not have anything to exile, hope you can hand attack their draw away.  Against Aggro this deck wins by surviving and removing threats; against Midrange/Control this deck wins by pure card advantage.  Against combo, you should have everything you need to remove their important pieces.

Sideboard Guide:

• Authority of the Consuls against hasty decks
• Requisition Raid against decks that use a lot of enchantments+artifacts together (insane value if you can get two for three mana).
• Another Dreams of Steel and Oil against creature heavy decks
• Anoter Duress during control mirrors or against players with a lot of sac/exile effects
• Pest Control against the menace, the pixie
• Split Up against anything that you want early curve sweepers for, that Temporary Lockdown doesn't cover, or you want to add in addition to.
• Wilt-Leaf Liege against discard
• Parting Gust against decks with a lot of sac/exile effects, to protect Ketramose as well as a removal spell in a pinch.  I usually sub it in against Domain Overlords.
• Another Cease // Desist against either Affinity, Domain Overlords, or graveyard strategies
• The End against Planeswalker-centric decks.  Haven't used this one much, might swap it for another Wilt-Leaf Liege because I hate discard effects.
• The cards you want to remove are going to be matchup dependent, generally I remove Anoints when against decks that don't run a lot of low mana threats (but I keep it if they have land creatures).  I remove Temporary Lockdowns often against higher curved decks (sometimes subbing in the Split Up); I also remove them if they can hit enchantments easily or it's too risky (such as against pixie, where they bounce it and get all their enters triggers again).  I might remove Kaya, Intangible Slayer against aggro where I don't need the late game inevitability.  Remove Duress against decks that mainly focus on creatures, remove Dreams of Steel and Oil against decks that don't run a significant amount of creatures.  There are some other flex spots that I've removed on occasion like Elspeth, Lord Skitter, and sometimes even a Legion to Ashes if they're a very fast deck.  Sometimes I drop a Deadly Cover-Up if it's too slow or not effective in the matchup (very rare).  I also sometimes run 61 cards after sideboarding if I don't mind a less consistent mana base (against lower curve decks).

Edit post Mythic: I'm currently hovering at about 89% Mythic; my thoughts on facing much more streamlined decks are as follows:

• Beza's lifegain and additional blockers are life saving.  I added another and am considering a third.
• I've removed Invasion of Theros as it was just too slow.  Even though you can flounder if you don't draw Ketramose, I find I usually can with 4 of.  It'll be a pity if you lose it though so be more cautious with him now.  Because I removed the invasion I also removed the Sheltered by Ghosts and Sporagenic Infection since you can't tutor those anymore (and I found Sheltered to be a dead card when I didn't have minions on the board, or I was going to wipe them).
• I increased the Temporary Lockdown count, just with the more aggressive decks I'm seeing it seemed necessary to always have one.
• Cease // Desist seems like a good way to survive a bit longer, and offset Ketramose pings.  I'm sure it'll come in handy against affinity and enchantment (such as Domain) strats as well.
• What this deck really needs is a strong two drop that draws exile effects and slows the opponent down.  Outlaw Medic is, I think, the strongest contender; since it's a somewhat ok blocker and gets some incidental lifegain which would help with Ketramose pings.  I've also considered Bladed Ambassador.  However overall I think these cards are too weak.  I'll have to experiment.  But if a really good 2-drop for this is released it could really be a tier 1 imo.

Tips:

• I run 4 Legions to Ashes despite it being a bit of a tempo loss, and sorcery speed, because it deals with anything I need it to.  Plus it can wipe tokens if you don't have a Temporary Lockdown.
• Target card draw first if you can.  This deck wins by card advantage.
• You've got 4 pieces of instant speed removal (2 Get Lost and 2 Anoint); don't waste them if you can help it.
• If you're seeing a lot of aggro, consider adding another Temporary Lockdown, upping the instant removal count, or do as I did and add a single Split Up (without removing any other cards; 61 is fine for jankers like myself)
• Hand attack is crucial for determining if you can slam a naked Ketramose; I've considered adding one or two more. (Probably another Soul Search since your turn two isn't critical and it has more flexibility)
• Be careful, the life drain from Ketramose is nontrivial; there may be times when you need to sequence to avoid a draw or two
• Ashiok does not draw off Ketramose, I usually drop the tokens when I bring her in, they close out games fast.
• Deadly Cover-Up is an all-star in this deck.  I removed a Sunfall to have 3 copies of it.  You can exile more cards evidence than necessary, to activate Ketramose, if you're unsure how many cards you will exile with the Cover-up effect.
• Land creatures can be quite annoying, save your instant speed removal for them; or up the count of Demolition Field.
• Plaza of Heroes has won me several games by simply leaving the mana up for it's ability to protect Ketramose.
• Know when you can just take it slow and pump mana into tokens with fountainport, such as control matchups.  In these matchups it's crucial you don't drop your Ketramose into a counterspell/exile effect since you absolutely need the card advantage.
• Slamming a naked Ketramose into a Ghost Vacuum draw is a play pattern I've often performed.  At least it replaces itself.
• Don't forget Ghost Vacuum is a win con, that is if a creature ever hits the yard.
• Don't forget Ashiok also has a mill win con, I have won with her ultimate (exactly once).
• I shouldn't need to tell you this, but against most affinity decks, save your spells that can target Simulacrum, for Simulacrum.

Changes I've tried or considered making that I'm still not sure about:

• You might ask: Why so many 1 ofs?  Well it's because I don't want dead cards in my hand because I already have a Legendary out.  And as far as the planeswalkers go, they all fulfill very similar roles and I couldn't really decide on any one that I wanted more of.    Bonus side effect of blunting Deadly Cover-Up collect evidence mode.
• I've slotted in Requisition Raid when I was seeing a lot of affinity and enchantment decks.  Can be clutch, but can also be a dead card.
• I've considered a couple Resolute Reinforcements as instant speed sacrifice fodder.  But I don't want to disrupt the formula because of a single deck that wrecks me.
• More Lord Skitter (another exile effect, maybe remove a ghost vacuum or unstoppable slasher)
• More Unstoppable Slasher (eats exile effects that could target Ketramose; maybe instead of Lord Skitter)
• Malicious Eclipse is a good card; but I just haven't found it good enough to run over the more versatile Split Up in my sideboard.
• I've swapped in Split Ups instead of Temporary Lockdowns at times as a lot of decks are running powerful 3 cmc cards.
• Ghost Vacuum is basically an extra card draw every turn when Ketramose is out; but I've only briefly considered upping the count to 3+.  It simply doesn't do enough on its own and you don't need more than 1 out realistically.