Deliverance of Itza is direct damage, therefore it can't be cast on units in combat; as it is a multi-unit targetting spell my opponent said that, as one of the 5 units within 12 inches of kroak was in combat I couldn't cast i as it would effectively target the particular unit that was in combat. This should be FAQued but if my opponent is right then his one spell is very situational.
The BRB says when talking about spell targeting that the default targeting rules (not in CC, LoS cone) only apply if the spell doesn't provide alternate targeting rules. DoI states it "targets all enemy units within 2d6 inches", which to me sounds very much like the spell providing alternate targeting rules.