Usually I dont post untested decks here, but I wanted to throw this one out there from a theory pov. In MTG, one of the most effective ways to answer aggressive decks is to go a little bigger, while still being fast enough to play beatdown against slower opponents. Here's a stab at a list that tries to accomplish this, with its sights set on Orc/Skaven.

I started with this:

Units (20)

• 3 Spider Riders
• 3 Lobber Crew
• 3 Clan Rats
• 3 Clan Moulder's Elite
• 2 Greyseer Thanquol
• 3 Deathmaster Snkitch
• 3 Ugrok Beardburna

Supports (16)

• 3 Warpstone Excavation
• 3 Contested Village
• 3 Contested Stronghold
• 3 Orc/Chaos Alliance
• 1 Orc/Dark Elf Alliance
• 1 Chaos/Dark Elf Alliance
• 2 Choppa

Tactics (14)

• 3 Innovation
• 3 We'z Bigga
• 3 Troll Vomit
• 3 Pillage
• 2 Tzeentch's Firestorm

This seems a fine place to start tuning, assuming bolt thrower isnt a menace in your metagame. The general idea is to disrupt and play supports early, leveraging Contested Stronghold to ramp ahead of your opponent, then start playing big, powerful spells like Firestorm, Troll Vomit, and Ugrok.

As a bonus, here's a list that adapts to thrower:

Units (19)

• 3 Spider Riders
• 3 Lobber Crew
• 3 Clan Rats
• 3 Clan Moulder's Elite
• 3 Deathmaster Snkitch
• 2 Grimgor Ironhide
• 2 Ugrok Beardburna

Supports (17)

• 3 Warpstone Excavation
• 3 Contested Village
• 3 Contested Stronghold
• 3 Orc/Chaos Alliance
• 3 Orc/Dark Elf Alliance
• 2 Choppa

Tactics (14)

• 3 Innovation
• 3 We'z Bigga
• 3 Troll Vomit
• 3 Pillage
• 1 Mob Up!
• 1 Tzeentch's Firestorm

As I said above, neither list has been tested at all.

Clamatius and I were speculating that a miser's Grimgor or two might actually be an effective answer to bolt thrower for orc/skaven, and the second list here is probably the best shell for accomodating him while playing the Skaven package. I'm actually fairly dubious; I think thrower can hold Innovations in-hand to play around Grimgor and recover in a single turn, or even worse, hit the orc player with a Flames to completely reset their Kingdom hammers post-Grimgor. To be fair, Skaven can certainly also hold Innovations, and thrower can probably only make this move once. So it might be good enough. But this is all speculation - I welcome others to give this strategy a shot and post what you think. It might be terrible! (there is definitely a non-zero chance that playing single-set has warped my thinking... support removal is much more scarce there....etc...)

This is quite similar to the Chaos/Orc deck that I've had in some version since the base set. The core of the deck being 15 supports, 3 Troll Vomit (from a Chaos board), 3 Lobber Crews, 3 Pillage, and 3 Rip / 3 Bloodthirster, and random beefy Chaos/Orc guys. The thing that I like about playing it off of the Chaos board is that you can run a couple of different multi-hammer supports (Warpstone Meteor and Banna of Da Red Sunz), which makes getting a big support advantage easier. It also makes Flames/Firestorm easy to cast. But with Skaven in the deck, you pretty much have to go for the Orc board to make sure you can cast Vomit for four. I think it's a tough call whether to go the Skaven route or not. They are working against the flow of the deck on basically every front, but they're just stupidly good.

In any case, I think Rip is definitely worth it, since it gives you a much-needed way to defend early attacks from other rush decks. Right now, Ugrock is pretty much your only defender. Having one defender is not much better than having none, since they will just attack a different zone or play Seduce or whatever. It's also randomly good against the Thrower, Judgment, mono-Dwarves, etc. And it's good for sneaking in damage after Vomit.