So I asked for sideboard help on Friday (thanks everyone).
Went with 1 Collective Brutality, 1 Hazoret the Fervent, 1 Wear//Tear, 2 Kambal, 2 Ensnaring Bridge, 2 Engineered Explosives, 2 Molten Rain, 4 Leyline of the Void.
R1 Storm (2-1): Game one I had Pyro, removal and Blood Moon. No discard. His early Opts and fetches Steam Vaults made me guess Storm. I made a mistake and played turn three Blood Moon and he had an Island and stormed me out. Game three a K Command on his Electromancer in response to a Desperate Ritual let him go for a while but eventually had him fizzle out. Rabblemaster took the game from there. Game three I hit him with a Leyline which seemed to surprise him and a Pyromancer took the game.
R2 Ad Nauseam (2-0): Game one I strip his hand, start the Rabblemaster beats. Force him to time walk me by playing a Blood Moon that he uses Pact of Negotiation on. He desperately Spoils for a Phyrexian Unlife and dies to it. Game two he starts out with a Leyline of Sanctity. I get a Pyromancer out followed by a Blood Moon and slowly take him down, targeting myself with Inquisitions to get tokens. He Angel Grace's to save himself one turn. Next I Tear his Leyline, Thoughtseize him, Angel’s Grace. He has one more discard it and Bolt him during his upkeep
R3 Burn (2-1) Game one he burns me out. Game two I take his Eidelons, and use Brutality to keep my life high enough that a Rabblemaster can quickly take him down. Game three he’s short on lands. I have a Pyro and both of my Molten Rains. He scoops after I blow up his two shock lands.
Draw into top 8.
Top 8 vs Eldritch Evolution: No idea what this deck was going for other than Reveillark, Wall of Reverence and Sigarda. Long game one where he eventually is just gaining 5 life a turn and swinging with Thrun and Sigarda and I can't keep up. Side in Leylines hoping to stop Reveillark and Ramanup Excavator shenanigans, Bridge for the big guys and Hazoret to block Thrun and get around a potential Leyline of Sanctity. Mull to five (both no land hands), no Leyline, stuck on two lands even after a Faithless looting. He's already fetching every turn for lands off of Excavator. I’m dead.
Go and buy myself another Inquisition of Kozilek so I have matching art. (The true key to success.)
R1 Tron (0-2):
He drops a Tron piece and a map. I Inquisition, he has Karn, Ugin, Ghost Quarter, another Map and a Forest. Karn comes out turn three and demolishes me. Game 2 I lead off with a Thoughtseize. He has Thragtusk, Stirrings, two Towers, Powerplant, Wurmcoil and Sylvan Scrying. My hand has two bolts, so I can handle anything but the Wurmcoil, so I take that. Goblinrabblemaster goes in hard. He never played the Thragtusk, using the green on Ancient Stirrings. I guess he was searching for something else that he couldn't find? Game three he leads with Tron and Map. I play land, pass. He plays Tron piece two. I play Young Pyromancer. He gets Tron and plays Karn, minus on my YP. Here's where I made a mistake. After fetching a Plains my hand was Land, Ensnaring Bridge, Blood Moon, Molten Rain, Bolt, Rabblemaster. I thought it out, decided to go for Rabblemaster for board presence. Should have bolted the Karn, probably, but he had another one.
R2 Merfolk (2-0): Game one a quick Vial gets him going with three (!) Silvergill Adepts but I slowly pick off his stuff and get a Pyromancer, Reveler and quickly overwhelm him when he's tapped out except for his Vial. Swing with all my tokens, he blocks and Vials in a Reejerey. After combat I use Collective Brutality on his Reejerey and then have to remind him all his Adepts die. Bedlam takes it from there. Game two I get a YP, then Rabblemaster. Turn four I Push his Lord while he has a Cursecatcher. He thinks, eventually lets the Push go through, figuring I’m trying to get something else with my remaining Mana. It's a bridge, though, and I manage that with Rabblemaster to not have my Goblins attack until I have a swarm that's too big. Knock him down to three with Bolt in hand, but one in his hand and mana up. Considering it's a Dispel, I let him untap, he plays an Adept, revealing a Lord, Bolt for win.
R3 KCI (0-2): This was my first time playing against the deck and I’m sure I made many mistakes. Turn one Thoughtseize he has 2 KCI, Myr Retriever, Chromatic Star, Mox Opal, Mind Stone, Grove of the Burnwillows. I guess I should have taken the Myr or maybe a KCI? But I took Stirrings. Next turn I top decked another Thoughtseize, took the Opal thinking to keep him off mana ramp, but turn two he goes off. Game two we both mull, I lead with an Thoughtseize. KCI, Grove, Spire, Terrarion, Mind Stone, Pyrite Spellbomb. Take KCI. He goes land, I draw a Wear/Tear and hold Blackcleave, Kambal, KCommand and a fetch. I play the fetch. He plays a Mindstone and Pyrite. I fetch for a shock and Wear his Mindstone hoping to keep him off mana. Turn three I hold up KCommand and pass. He plays Blood Moon. Was not expecting this at all. Blow up his Mox and make him discard. Should have blown up his Pyrite but for some reason I thought it did one damage and not two, which matters because I play a Rabblemaster next turn which he kills. Whoops. Then he just beats me with Myr Retrievers while I Faithless Looting into nothing but unplayable spells and then he EEs his own Myriad Retrievers and combos off. Lots to learn about this matchup.
R4 RG Eldrazi (1-2): Mulligan down to five game one. Drag it out with a Blood Moon but he gets me. Game two I strip his hand down and beat with Spirits, Molten Rain his Eldrazi Temple to win after he tries to stay alive with an Ooze. Game three I mulligan down to five with a Pyromaster, a Bridge and land, Faithless Looting on top. He just accelerates really fast and I’m dead.
R5 Enduring Ideal (2-1) Almost ask to ID just for the PWP and to go home early. I Inquisition a Pyrenean Unlife out of his hand turn one then get in with Pyro and Spirit beats, with a Blood Moon to slow down his Nykthos. hHe plays Ghostly Prison to give himself time. He casts Enduring Ideal, gets Form of the Dragon. I have KCommand and Bolt in hand. I had no idea what to side in. Hazoret for non targeted damage, EE to take care of trouble enchantments, Kambal because he's mostly non-creatures, Molten Rain for utility lands and Wear//Tear because I can get rid of one enchantment? He opens up game two with a Leyline of Sanctity. Then enchantment after enchantment, with a Luminarch Ascension which finally ticks up to four when he has too many Ghostly Prisons and such for me to attack and I die to angels. Bridges come in and I pray. No Leyline after he mulligans game one. I drop a turn three Kambal. He responds with Ghostly Prison. Get in one attack and he casts Gideon’s Intervention naming Kambal, but hey, loss of life is not damage! I get out a Pyromancer which gets named with Runed Halo. Hardcast Souls for some beats, he eventually gets Wrath of God. I put out another Pyro, flashback Souls. Next turn I Tear his Ghostly Prison, swing with the tokens. He draws and scoops. Was one short of having the mana to cast Enduring Ideal.
Ultimately not sure about the sideboard, but I did play a lot of different stuff. Everything ended up being useful at some point, Engineered Explosives probably the least used but still useful. Leyline I’m still up in the air on. Great when it gets there but sometimes you just don't have it and how hard do you mulligan?
Maindeck Rabblemaster really helped put on pressure in the games where I needed it, though. Didn't entirely miss either Liliana, but I think having access to them might have proved useful in some cases. Not sure where to take the deck for my next PPTQs or even stick with Mardu or not.