Thoughtseize over Duress. I do believe the life loss is still relevant, I find I win a lot of games with Necro and Yawgmoth's Bargain, however I've also come to realize that it might be a necessary evil. Thoughtseize deals with Eldrazi's threats, while also dealing with all the other problematic cards. Cabal Therapy is too much guesswork against Eldrazi that have so many different threats you have to deal with. Did the lifeloss come back to bite you at any point?
I ended up cutting Library of Alexandria, this could be incorrect. But I just don't like playing the card against anything except control decks, and you should be strong against them anyway. The Island helps you against your harder matchups and frees up sideboard space.
My matchups were Merfolk, Eldrazi, Humans, Mentor, Eldrazi.
I believe my sideboard was ill equipped to deal with multiple hatebears that were not artifact. I was lucky to dodge multiple Thalias and Vryn Wingmares. Against humans and Eldrazi I've often had to try and find my single copy of Chain of Vapor, and I think it might be necessary to have another one in the board. I'm also thinking some copies of Massacre or more likely Dread of Night should find slots in the board. You might not need it against Mentor, but having a single copy against them can stop them from doing a lot.
Merfolk is a tough matchup imho. G1 he went turn 1 chalice for one, but ended up discarding cards for a while. I tried to resolve a Yawgmoth's Bargain, but he had the Force. G2 I kept a super bad hand that in retrospect I should've shipped. Chain of Vapor, Mana Crypt, Mox Sapphire, Hurkyl's Recall, Black Lotus, Gitaxian Probe. I end up scrying and seeing a Tendrils of Agony. The probe sees a bunch of null rods and awful permanents for me, but no countermagic, and I just kill him. I don't remember game three, I was way to happy about turn one killing him with nothing but natural storm ^^,.
My second match was Eldrazi: My opponnent mulled to 5 in game 1, and didn't have a lot of pressure. This gave me enough time to find what I needed and murder him. Game 2, Eldrazi did what it was supposed to do and I get rekt. Game three keep a hand that has the possibility of going turn 2 necro, but he goes turn one Revoker naming Necro. He draws a lot of artifact threats and I've kept a Hurkyl's in my opener. I end up being able to hurkyl twice and necro twice. He could never put down more than one artifact hate piece every time I hurkylled, so I ended up playing through whatever he played.
Third match was against Humans: Game 1 I manage to find my singleton chain of vapor in my opener, which was nice since he went turn one thalia. After a few turns of setup, I manage to bounce it and play Yawgmoth's Bargain to win from there. Game two is pretty much the same, but after 15 cards with Bargain I'm still struggling to find a win condition. He's got a Thalia and a Leonin Arbiter. I have to spend a couple turns hoping he draws nothing, paying 8 for my dark petitions so I could tutor up answers. He doesn't draw anything awful for me, and my goblins that I played earlier held off his aggression.
Mentor: G1 I demonic tutor for a mind's desire because he was tapped out. I play out all my mana and resolve it for 6 copies. I could've killed him had I gone for dark petition or yawg will, but that would not have played around force of will, so I took a riskier line. I ended up getting lands, ritual and a necro, so I was dead to a force anyway. Fortunately for me, none was to be found. Things get out of hand from there. Game two I keep: Swamp, Mox Jet, Defense Grid, Dark Ritual, Necro. I go turn one defense grid, he forces. I go turn two duress, he misteps, and I ritual for necro, he has another force. From there he plays gush, treasure cruise, dack etc. Things got out of hand. Game three I get to play a turn one defense grid and a timetwister, that shuffles away his Stony Silence. I probe and duress away his preordain, leaving him with ancient grudge, dack, two moxen, and lands. Next turn he plays Dack, draws two, and grudges my grid. Next turn I go for Yawgmoth's Bargain, he gushs in response, but finds no Force, he had no mana open so I went for it. It resolves and I draw 14 cards, 5 of which were moxen, and I already had the tendrils in hand. A hurkyl's later and he's dead.
Eldrazi: I thought my opponent was on dredge, and I have a turn one kill with lotus and some other artifact mana. My opponent goes turn one null rod. I only have one fetch land in hand, but I have my vampiric tutor (for chain of vapor) in hand. Unfortuantely I can't crack my land to find a sea, because he has a wasteland. Fortunately for me he goes for a smasher the turn after. I tutor for chain. I chain his stuff. Play lotus, rituals and dark petition for yawg will.
Game two: I probably wouldn't have kept this if we hadn't already split prizes. But my hand was: Ancient Tomb. Dark Petition, Dark Petition, Dark Ritual, Dark Ritual, Hurkyl's Recall, Duress. He says: I hope you don't turn one me and plays Eldrazi Temple. I draw underground sea. 2x ritual, into petition for lotus, petition for yawg will, play lotus, play ritual, play dark petition for tendrils, ritual, take 22.
I'd like to say that I was a bit lucky to draw my Chain of Vapor at opportune times, and I kept some sketchy hands. All the games I played were a lot of fun though. I do believe I might have to start playing some Thoughtseizes soon, and definitely some answers to Thalia and Vryn's Wingmare, which are going to pop out more going forward.
@BrainStoyrm on twitter