If i attack with Kaalia of the Vast and use her ability to bring out Utvara Hellkite, do I get the 6/6 red Dragon or do I have to declare him as an attacker?
508.4. If a creature is put onto the battlefield attacking, (...). Such creatures are “attacking” but, for the purposes of trigger events and effects, they never “attacked.”
RULES OF MAGIC :
http://magic.wizards.com/en/game-info/gameplay/rules-and-formats/rules