I attended Da Boyz GT recently and used these tactics to go 5-1-0 and get tied for second overall. My loss was to our very own Darkwynn. It’s the second time he has gotten the better of me at table one to win a national event. Next time Nick. Next time.
You need to find an enemy unit and vehicle which are close together. The unit should essentially be a pushover in assault, the vehicle cannot have a weapon skill. Strike squads, or shooty inquisitorial henchmen with their transports are both good selections. These units both need to be in striking distance of your assault unit.
Now we need to do the ground work. If my enemy unit I want to assault is in a transport like the pic above, I need to prepare to fire my ranged anti-tank firepower at it in order to demount them so I can get locked in. I also need to position my assault unit correctly. They should be in place such that the majority of the unit can assault the distracting vehicle, and a few can assault the target assault sissy unit.
Declare an assault on the closest target, tank or unit. This is important only if you don’t think you will make it into assault with one of the targets, or if you are going through difficult terrain. Now here is the key part: Place as many of your models as possible such that they may attack the tank. You are still obligated to engage as many of the enemy models as possible, but engage is defined as “base to base, or within 2” of a model who is in base to base”. Depending on how clustered they are, you may be able to do this with one model.
Now it all falls into place. The combat with the unit results in a draw or a narrow victory/loss which the leadership check is passed easily (Be careful with codex marines and Combat Tactics here). You may or may not destroy the vehicle, it doesn’t really matter. Since your assault unit is still locked with their unit, and the vehicle does not have a WS and therefore cannot lock you in assault, the Kommandos are forced to engage the enemy unit. Now that you have brought your powerklaws to bear and additional grunts in, you have an excellent chance of wiping the enemy unit or forcing them to flee in the following (your opponent’s) assault phase, leaving you free to act in your next turn.