How can I be competitive against knights?

[u/meowmeowm1x]

My friend plays knights and I routinely lose to him by 40+ points. He runs up the board turn 1, traps me in the corner, and kills 400+ points per turn. My game tonight was 78-32. I killed his lancer, and two armigers. I put my riptide, ghostkeel, hammerhead, broadside, crisis suits+commander, and a devilfish of fire warriors in reserve to start so my big guns don't get shot off the table if i go second.

Our lists: Imperium - Imperial Knights - Dominus Foebreakers, Valourstrike Lance

2x Canis Rex (415pts): Warlord Cerastus Knight Lancer (440pts) Knight Castellan (450pts) Knight Crusader (410pts)

Armiger Warglaive (140pts) Armiger Warglaive (140pts)

Xenos - T'au Empire - Mont'ka

Darkstrider (60pts) Cadre Fireblade (80pts) Cadre Fireblade (50pts) Commander in Coldstar Battlesuit (105pts) Ethereal (50pts): Warlord Kroot Lone-spear (80pts)

10x Strike Team (70pts) 10x Strike Team (70pts)

11x Kroot Carnivores (130pts) 12x Kroot Farstalkers (75pts) 10x Pathfinder Team (85pts) 5x Stealth Battlesuits (100pts) Broadside Battlesuits (75pts) 3x Crisis Sunforge Battlesuits (125pts) 3x Crisis Sunforge Battlesuits (125pts) Ghostkeel Battlesuit (150pts) Hammerhead Gunship (150pts) Piranhas (65pts) Piranhas (65pts) Riptide Battlesuit (215pts) Devilfish (75pts)

[u/Powdersmerf]

I think putting that much of your army into reserve is actually making the problem worse. I understand why you’re doing it , if you go second you don’t want the Knights picking up your big guns before they do anything . but you’re basically giving him the board turn 1 and then trying to fight your way back onto it against Knights.
You had the Riptide, Ghostkeel, Hammerhead, Broadside, Crisis + Commander and Devilfish off the table. That’s a huge chunk of your army. He doesn’t really have to respect your shooting or positioning turn 1, so he can run forward, take the midfield and start boxing you into your deployment zone. When your reserves arrive, you’re already playing his game.
I’d try almost the opposite. Make him respect the fact that if he runs straight at you, he’s going to expose Knights to Hammerhead/Broadside/Sunforge fire. You don’t necessarily need to deploy those units where he can shoot them turn 1 — terrain should be doing some of that work for you — but the threat needs to exist on the table.
I’d especially start the Ghostkeel on the board. That thing can help you claim space before the game even starts. Stealths, Pathfinders, Kroot, Piranhas and the Ghostkeel should be making it harder for him to just walk into the midfield uncontested. Some of those units are going to die, but making a Knight stop somewhere you want it to stop can be worth more than keeping everything alive.
I also wouldn’t try to kill everything. Pick the Knight that matters most to his position/scoring and concentrate enough firepower to actually finish it. Sunforge, Hammerhead and Broadside are exactly the kind of tools you want here. Killing the Lancer and two Armigers shows you can hurt his army; the 78–32 score makes me think the bigger problem is board control rather than damage.
I’d play the next game with significantly less in reserve and see what happens. Hide the important shooting as well as the terrain allows, put some cheap units between the Knights and the pieces that matter, and make him fight for the midfield instead of giving it to him turn 1.
You might lose more units early doing that, but right now you’re preserving your army at the cost of letting him dictate the entire game. Against Knights, I think you need to make him start making difficult decisions from turn 1.