If I don't want to play a unit or there are no more cards in my hand,can I still be able to declare target for conducting a battle or a siege?

Thanks for reply...

Normally, a player performs a Combat action by playing unit cards from his hand (like performing a Spend Gold Action by playing gold cards). Do you have a specific idea behind this question ?

After reading the rules, you may pass (step 2) after Declaring Target (step 1). But after passing, you cannot play any more cards so the defender automatically win (0 versus 0).

Specific ideas:

1. Using the +2 strength of the event deck without wasting a unit

2. Using the Dragonrune card which allows to deal 1 damage after the siege of a homerealm (doesn't say "successful siege")