Built GBr and went 2-2 in matches. This was a rough pool. My good blue cards were Time of Ice, Deep Freeze, and Cloudreader Sphinx and pretty much nothing else. My white had a bunch of medium creatures, but nothing exciting and no removal. Black was probably my best color because it had a few removal spells, but most of the creatures were not that special. Green had a bit of fixing and ramp, but almost no payoffs. Red had some of my best cards and almost nothing else noteworthy. So I ended up spanning 3 colors to try and juice up my power level and I still feel like the deck was pretty weak. I had 2x Yargle, Glutton of Urborg and 1x Urgoros, the Empty One that I did not play, but I wonder if I should have tried them. I think they're better when you can give them evasion which I couldn't do. The list I added is the final form, initially I had 2x Adventurous Impulse and 2x Llanowar Scout but I felt they weren't impactful enough because I didn't really have any great creatures to dig to (except for Siege-Gang Commander) and not many ramp payoffs.
EDIT: After thinking about it for a bit, I'm pretty sure it was a mistake to go green and I should have instead been pure RB. Going green didn't give me any removal, gave me some ramp, but I didn't really have any payoffs anyway. I think I might have overvalued the two green Sagas I included. I don't think they're bad by any means, but I think playing green didn't improve my deck enough to justify 3 colors. I still think this was a tough pool though and that picking up many more wins would have been difficult no matter what.
MATCH 1 vs GBw (2-0)
Game 1 was nice I was able to put Helm of the Host on Windgrace Acolyte and gain lots of life and deals lots of damage with my flying army. Game 2 was closer, opponent mulliganed to 5, so I deployed my Stronghold Confessors on turns 1 and 2 and started beating down. Eventually things were looking grim for me and I went down to really low life. I fortunately drew and cast Mammoth Spider before his Kazarov, Sengir Pureblood came down. Luckily for me, my opponent's only red source was Navigator's Compass and my Helm of the Host eventually created enough Mammoth Spiders for me to kill my opponent after I drew Eviscerate to take down the vampire.
MATCH 2 vs UW (1-2)
Game 1 wasn't very close. My opponent got down 2x Mesa Unicorns and Sanctum Spirit early on and I couldn't deal with them and racing was impossible due to all the lifelink I was facing. Game 2 went better for me, I was able to put Helm of the Host on Knight of Malice early on and eventually overwhelm my opponent with 3/2 first strikers. Game 3 was rough, my Helm of the Host got Syncopated and icy manipulater did work against me. I couldn't really get anything going and eventually took the loss.
It was at this point that I changed my deck construction with -1 Swamp -1 Skizzix and +1 Mountain +1 Primordial Wurm. My red cards kept getting stranded in hand and I figured I could skimp on the swamps because I only ever needed one in play.
MATCH 3 vs GB (0-2)
Game 1 stalled out pretty quickly as we each cast Mammoth Spiders on turn 5. We sat around for a few turns deploying creatures until my opponent cast a kicked Grunn, the Lonely King. Between his attacks, removal, and Icy Manipulator my army of creatures dwindled and I lost. Game 2 seemed to be going better, but then my opponent landed a Yargle, Glutton of Urborg. Luckily I was able to cast a Windgrace Acolyte to block it, but it was removed. And so was my other Windgrace Acolyte the next turn. And so was my next blocker. My opponent cast 3 Vicious Offering and I didn't stand a chance.
MATCH 4 vs GW (2-0)
Game 1 went well, I was able to equip Helm of the Host to Mammoth Spider and eventually beat down, however, my opponent used auras, equipments, and Triumph of Gerrard to grow his Shanna, Sisay's Legacy very large. I was able to absorb a few hits and then have Siege-Gang Commander toss goblins at the remaining blockers to clear the way for 5 Mammoth Spiders and the rest of my creatures to crash through. Song of Freyalise really helped because the goblin tokens tapped to help add the necessary mana for Siege-Gang Commander activations. Game 2 wast more tricky. I was able to Helm of the Host on Windgrace Acolyte but my opponent brickwalled my flyers with Shalai, Voice of Plenty. Things were looking pretty bleak until my opponent let me kill Shalai, Voice of Plenty by double-blocking. I was feeling alright but then my opponent wiped the board with Urza's Ruinous Blast. I drew a timely Vicious Offering to kill the leftover Shanna, Sisay's Legacy and was able to fairly quickly rebuild. After that I quit making Windgrace Acolyte tokens (I was worried about decking myself at this point) and made a Mammoth Spider instead. At the end I was able to live the dream and put Helm of the Host on Siege-Gang Commander, but by then I had enough attackers for the kill.
All in all my deck was able to ramp very well, but I rarely found ways to take advantage of that mana. Things went well when I was able to use Helm of the Host, in fact, I don't think I lost a game where I was able to equip it.
THOUGHTS
Siege-Gang Commander is amazing and I wish I drew it more often. Especially filthy when equipped with Helm of the Host.
Grow from the Ashes surprised me. I liked saving it until I could kick it, but it's good on turn 3 as well. I like how the lands come into play untapped. Often allows you to hold up removal.
Caligo Skin-Witch seemed decent. It blocks well early and can annoy your opponent late.
Krosan Druid was weird. With how much my deck was able to ramp, I never drew it to gain the 10 life. When I wanted the 10 life I was always a couple of mana short.
Wizard's Lightning was great. I expect to draft red in this format a few times and hopefully I'll see a lot more of these.
Eviscerate does the job, man I wish it was an instant.
Vicious Offering is incredible. It's probably one of the best commons in the set. Unfortunately I was usually on the receiving end, but it does everything you want it to. Kills threats early and scales well late.
Helm of the Host is amazing. One of the best cards in my deck. Generates unreal value and helped me not only close out games, but it also helped me stabilize a few times.
Mammoth Spider amazing blocker, I suspect this will see lots of limited play.
Stronghold Confessor x2 was very impressive. I like this guy on turn 1 and turn 4+. I want to try and draft a million of these sometime and just go crazy with menace. I think you often want to cast these with kicker, a 3/3 menace is really great.
Knight of Malice was great and definitely shined in certain games. I think this card will be insane if you can draft BW knights and pair it with Knight of Grace.
Windgrace Acolyte x2 was great. I love the lifegain attached. These can close out games quickly, but they are very vulnerable. Most of the removal in the format takes these guys down.
Song of Freyalise was decent, but I think needs a bunch of kicker cards and mana sinks to really shine.
Llanowar Scout x2 was ok, it helped accelerate some creatures out sometimes, but I think my payoffs for it were too few and too weak in general. I think this has a place though, it blocks well early and can boost you ahead on mana a turn or two.
Adventurous Impulse (initially x2, then down to x1) was hard to evaluate. I thought it would be much better than it played out most of the time. Maybe that's because so many of my creatures we lame and my creature count was sort of low. It did help clear chaff off the top of my deck a few times so maybe it's better than I think.
I was unfortunately able to ever cast The Mending of Dominaria, but I often wanted to draw it and use it. I love how it can help you grind by "drawing" you creatures and then super ramping you. I really wanted to hit the third chapter after dumping tons of lands into my graveyard with Windgrace Acolytes, but I never pulled it off.