Post rules you know of but haven’t ever had to do.
Deliberate immobilization (such a small chance of it working)
Scaling (haven’t seen the situation yet that needed it)
How can one go without ever using Deliberate Immobilization? It’s critical in at least half of all scenarios with armor. Look for these circumstances as prompts to use DI.
1) If your MA cannot penetrate enemy armor with a roll of 5 then go for DI.
2) If enemy armor has red armor numbers - their AFV are big - consider DI.
3) If your small MA has a high ROF, or the chance for multiple hits at 40mm or less, then go for DI - the multitude of dice rolls these circumstances trigger dramatically increases the chance of a successful DI.
4) Russian ATRs, especially when within two hexes of a stationary target, are serious DI threats against pre-43 German armor. They remain a threat against Mark IVs throughout the war.
I see DI used successfully in about half of my games.