Niche D20At the start of combat, each creature must make an initiative check. An initiative check is 1d20 + the creature’s initiative modifier. A creature’s initiative modifier is their Agility modified plus any other bonuses they have to initiative such as from feats, items, or other sources. In combat characters act in order, counting down from the highest resulting check to the lowest, before starting a new round and beginning again from the top. Characters follow this same order until the end of combat, though some actions may allow a character to change their place in the initiative.
If two or more creatures have the same initiative check result, the tie is determined by the highest initiative modifier used in the check. If a tie still exists, then tied characters should roll to determine who goes before the other; continue rolling as additional ties occur. This tiebreaker roll does not replace the initial initiative roll.
If an ability would add from, subtract from, or replace the initiative check the creature rolled after the results and turn order have been determined you may adjust the initiative check and re-determine the character’s position in the initiative turn order, handling any ties as stated above as normal.
Even if you can’t take actions, you retain your initiative score for the duration of the encounter.
A Round of Combat:
A single combat round represents 6 seconds in the world; making 10 rounds equal a minute of combat. This value is not adjusted if there are less or more creatures in combat at the same time, as it is assumed most actions within a round are happening at the same time or within rapid sequence of each other.
Each round begins with the character with the highest initiative then proceeds in order from highest to lowest initiative. When a characters turn is up in the initiative sequence, the character may perform their round worth of actions. A character cannot take an action outside of their turn outside of Reactions and Readied actions.
When an effect lasts for a number of rounds the effect starts on the initiative it began on, and ends just before the same initiative count that they began on.
Surprise Rounds
When combat starts, if a creature is not aware of their opponents but they are aware of you, the creature is surprised.
How to Determine Awareness
Generally awareness is determined if a creature was unseen, stealthed, or otherwise not successfully spotted by a perception check. Awareness is not limited to a single side of a combat, and some combatants may be aware, all may be aware, none, even with some on each side unaware. Usually if a creature is hidden or is actively attempting to hide a perception check is needed to determine awareness. If no one or everyone is surprised, no surprise round occurs.
The Surprise Round
If some, but not all, of the creatures in a combat are aware of their opponents, then a surprise round occurs. A surprise round is similar to a normal round of combat, following initiative sequence as normal. Creatures who started the battle aware of their opponents receive 3 action points instead of the usual 5 for their turn. Creatures may also take free and a single reaction during this time. Initiative order is followed as normal during a surprise round, simply skipping over the turns of creatures who were unaware during the surprise round.
Flat-Footed
Once combat has begun all creatures are treated as flat-footed until they have had a chance to act. Once a creature takes their first turn in combat they are no longer flat-footed for the remainder of combat; some abilities may allow a creature to be treated as flat-footed after this, with the ability specifying the duration of this effect.
When a creature is flat-footed they cannot use their Agility bonus or any dodge bonuses they have to AC. Some abilities and class features may allow a creature to avoid being flat footed at the start of combat. In addition, a flat-footed character can’t use reactions. Being Flat-Footed is not the same as a character wearing heavy armor not gaining their Agility bonus to AC, and as such despite wearing heavy armor retain dodge bonuses or any other bonuses that would be lost when Flat-Footed besides their Agility.