Why is there a Defensive Maneuvers Action Card?

Um… to enable you to perform defensive maneuvers.
Except for Gryphons, who have this as a faction ability, there is no way for you to easily redistribute troops between turfs you control—and this is by design.
Unicorns can defensively maneuver troops from one adjacent turf when attacked.

Further, if you find you’ve spread yourself too thin or wish to consolidate troop strength in certain areas, this Action Card enables you to achieve this.

Can you negate a Kraken attack if you have 3 or fewer troops?

No. You are not able to play a Combat Card in that scenario and as such, cannot play a Negate Attack Combat Card.

Can Dopplegangers clone any faction’s ability?

Yes. Cloning is limited, however, to the factions currently in play.

What happens if a faction tries to steal/discard my Zero Combat Card?

Th is is not possible. A “0” can never be stolen. Save time and remove it from your hand if someone needs to steal or discard your Combat Card.