Placing Shooters in keep during tactical phase

might-and-magic-heroes-6

I'm having one troubling question. Just as the title. During my campaing as haven i have noticed enemy is placing liches during tactics in the keep before the actual combat starts. I would like to do the same but i cant, when i place unit(archer for example) the unit disappears from the battlefield indicating that this unit wont take part in the combat.
If anyone know how to do this, please help me.

Best Answer

As far as I have been able to determine, you can't: you have to burn your unit's first move to enter the tower. I suppose it's another hidden buff the AI gets to offset its general lack of tactical or strategic ability. I would love to be proven wrong though.