Hero Turn Order

Not sure if this has already been asked, but do the Heros always have to act in the same order, or can it vary from round to round? Let’s say Haka had initially gone first in round 1, but now there’s a new minion in play. Can another hero first soften him up so that Haka can finish him off (and add to his Savage Mana) in the same round?

According to the rulebook it always goes clockwise from the villain.