I keep hearing people say that Wrenn and Six is a terrible card; however, this decklist I have below won twice in an oathbreaker six player matchup. I basically built it like a Zoo deck. What do you guys think?
People keep saying the most expensive card in modern horizons is terrible?
I've got a wrenn oathbreaker decklist as well, which unfortunately I haven't actually gotten to play yet. But your list looks very...unfocused. I don't really see any overarching strategy besides beating face with relatively mediocre creatures. Which is fine for a low-powered meta, but I don't see how you'd be able to hold up against a faster deck.
You're also missing some extremely useful auto-includes - especially all the fetchlands, which you could be forgiven for not having the budget for, but you also aren't running the cycling lands, which are quite cheap. Tectonic reformation wouldn't even be necessary if you were running forgotten cave, tranquil thicket, etc. Hell, if you don't want to shell out for real fetches, I'd probably at least include terramorphic expanse and evolving wilds. As your deck looks now, it seems almost impossible to get value out of W&6 when cast on turn 2, which imo is a big part of the point of playing them, having a reliable T2 play that can generate constant value through a fetchland or cycling land (or a strip mine/wasteland situation).
I'm pretty sure W&6 is one of the most powerful options in the format when built with a cohesive plan in mind to take advantage of their low cost and ability to generate value, but I don't see how a midrange zoo build is going to do that, basically.
EDIT: Having thought about it some more, I think I've narrowed down the problems with the deck into something more helpful.
Wrenn and six's most important ability is recurring lands. You have very few ways to get lands into the graveyard, and most of them are slow and take a long time to get going. On top of that, you can't really abuse wrenn's ult either. Basically, Wrenn makes no sense to helm this particular deck. A commander who springs to mind for me, and makes far more sense is domri, anarch of bolas. He synergizes with your deck immediately, his fight ability works well with your fat creatures, as does his mana ability, and it would let you cut your counterspell protection.
You might also consider switching arachnogenesis for something more aggressive that isn't so bad when it's being telegraphed - lightning bolt, decimate, something like that. Maybe Pyroclasm if you're having trouble with aggro. Something more along those lines, though. Arachnogenesis is a fine card but it's defensive while your deck looks offensive. You could also go crazy and go spider tribal with arachnogenesis as your spell, of course, but that'd require some big changes for your deck.