I keep hearing people say that GS and Tomb Kings is a bad matchup for GS because they don't have much that can take out big armored constructs and the Ushabti Greatbows rip infantry to shreds. I decided to do some tests and took to the custom battle mode to see how effective units could be against them. For the purpose of the tests I kept each side at a similar cost give or take 100 gold sometimes.
First I tested possible solutions against large heavily armored constructs.
The Sphinx of Usekph:
6 rock lobbas . Result: Pitiful, most of the rock missed and almost no damage was done before the sphinx was ripping through my lobbas.
3 gobbo flyers (whatever the hell they're called): Better but still awful. At least they could hit sometimes but they didn't do much damage. Definitely not any kind of reliable solution. (Wasn't too surprised by either of these).
The spider queen: Beat the sphinx of Usekph. A heavily armored monster being used to beat a heavily armored monster? Who would of thought? The spiderlings helps lower the sphinx's morale and confused his attacks. I tried a straight fight without spiderlings and still won.
2 units of savage orc big 'uns: Surprisingly they wrecked the Sphinx. Really quickly. I thought it wouldn't work that well with only 8AL but they went to town on the thing. Lost 30 Big 'Uns before the Sphinx was dead.
2 units of savage orc big 'uns board riders (whatever the f): also took it down. Tried it with cycle charging but still lost more health than with just the infantry variety surprisingly.
Tried rusty arrers, mangy mauraders,2 gobbo arrers and a 2 groups of gobbo spears and the sphinx got taken down pretty quick. The sphinx never even made it to my 2nd line of gobbos.
Tried a regular giant spider: It beat the sphinx pretty soundly.
Tried a giant: The giant died (unsurprisingly) but it got the Hierotitan to about 1/6th of it's health. Considering the Hierotitan is 400 more than the giant I think that was pretty decent.
Giant Spider: The spider won but it was pretty close so I think it could go either way.
Giant: The giant got WRECKED. The Warsphinx's animations actually knock the giant down quite a bit and it's archers continually pump out damage while the giant is lying on the ground. I was not impressed.
Giant Spider: About even. Lost one, won one.
But of course it's all well and good to say "counter big armored constructs with big armored monsters" but tomb kings get the greatbows which wreck armored monsters so it's not always viable even though I think the spiders are more effective by just a little bit on a 1v1 situation. So what counters greatbows?
For these tests I tested against 1 unit of chosen of the gods and 1 unit of regular greatbows.
I tried lobbas: Got wrecked
I tried flyers: Got slightly less wrecked
I tried savage orc big 'uns. They made it and took down the greatbows but one squad was down to about a 3rd of it's health by the time it engaged and in a real battle there would be a whole front line to get through. Obviously if you can flank and get in they will beat the greatbows (but I think everyone already knows this).
6 wolf riders: They took down the greatbows. Once the greatbows were surrounded they crumbled pretty fast. But in a real battle what are the odds of sneaking in 6 wolf riders into the greatbows? Still useful to tie them up with one group of wolf riders though while your front line advances.
5 savage orc arrers: They won but it wasn't pretty. Each squad was down to about 1/3rd or less of health. If the comp had focused fired I think it would have been a loss (I did use focus fire).
4 savage orc arrers: The greatbows wrecked them.
5 gobbo arrers and the rusty arrers: They absolutely wrecked the ushabti. I think this is a viable counter.
6 gobbo archers: They still killed the ushabti but they were pretty tattered by the end. Still, 6 gobbo archers cost 2250 and the chosen and regular greatbow together were 2350. Gobbo arrers only get 1 AP but all units get a garunteed 1 dmg so really it can be considered as 2 AP. 2 damage x 120 means you have the potential to do 240 dmg per volley. That times six and you can actually take the ushabti down. This still took awhile though, the 2nd group of Ushabti ran out of ammo at the end so not sure it's that useful in real life.
For fun I tried 8 gobbo spears. I just sat them there taking fire. The greatbows didn't even get rid of one unit and then were out of ammo and got wrecked. Silver shields and huge number for ya.
So what does this tell us?
I think it tells us that GS do have the tools to deal with greatbows and large armored constructs but it takes some good tactics and micro. Savage Big Un's will wreck constructs...somewhat surprisingly but also GS can bring equally powerful armored monsters themselves. Rusty arrers and a couple gobbo arrers will take out a greatbow unit of similar cost pretty easily (the chosen less easily but they can still do it). If you bring big un's and rusty/gobbo arrers the Tomb Kings player will have to decide wether to take out the big un's to save the constructs or the arrers to save the greatbows. Either way you have something to work with, either a good frontline of construct disassembling orcs or a greatbow counter squad. Same can be said of bringing heavily armored monsters/arrers.
Usually you want to try and get archers to hit low priority targets but even more so with greatbows. They're low archer and ammo count mean they really need to be hitting valuable targets to get value. If you can get them to shoot at gobbo spears, either by keeping most of your army hidden in forests or by continually moving your army back but keeping the gobbos in range of the greatbows then you've already won the greatbow war. Each arrow they fire into a gobbo spear unit is wasted value.
I'm no top 100 player or anything but I think if you had Azhag on his wyvern (it is fast enough to dodge greatbow fire), rusty arrers with some gobbo arrers, several savage big 'uns, couple gobbo spears to eat greatbow fire early game, orc boy big uns and maybe some skulkers should tomb guard make an appearance (I figure the stalk will keep them safe from arrow fire while advancing) and the mangy marauders you would do just fine.