Combat starts when a aggressive action is made and is responded by a aggressive action from a different source.

When this happens after the first attack.

• Roll for the Response order.
• The creature with the highest Responds goes first, following the Response order until it reaches Response order count 0.
• When a Response order ends 10 seconds have past.
• The Response order is reset to the highest count and continues this way until one group beats the remaining hostile creatures. (this can be by killing, forcing a surrender, or making them flee).

Combat can also be started when the first aggressive action is a surprise attack.
This means that the target must be unaware of the attack.

A creature that suspect an aggressive action can roll an insight skill check to be allerted and not suprised for the attack.

When one or more creatures are attacked unaware the following happends.

• The first creatures that attacks may roll one attack freely out of the Response order With +1A as its target is Suprised.
• All attacking creatures including the first one now roll for the Response order.
• The first attacking creature finish its turn as normal.
• All creatures after the first attacking creatures gets an suprise attack round (gaining +1A on their attacks).
• When the Response order count reaches 0, all remaing creatures will roll for the Response order. They are still Suprised until the start of their next turn.
• Combat resumes until one group beats the remaining hostile creatures. (this can be by killing, forcing a surrender, or making them flee).

Special Response Order counts are their to change the dynamic of the encounter.
They are the following:
Response Order count 30; Divine and Celestial effects.
Response Order count 10; Lair actions.
Response Order count 0; Magical effects.

Two creatures go head-to-head on trying to get the highest skill roll.
This can be against the same skill.
Or two different skill.

In both cases the highest check wins.

by a draw reroll till you have a winner

When two creatures are making a contested skill check against each other.
they do not win by simply winning the check
On the first check when a creature wins a check it gains 1 point.
From this point on, when a creature wins a check it gains 1 point and the other losses 1.
Both creatures roll until one creature has 2 points and win the contest.

In combat both creatures share the same Reaction turn of the slowest creature until the contest ends.
Other creatures have their turn as normal.
Creatures that attack and damaging one creature that is in the contest will give that creature +1DA per damaging attack taken on the next contested roll.