Surprise

RC pg 189 to 191

1. Determine Surprise - ...If any creatures notice enemies w/o being noticed in return, the aware creatures gain a surprise round.

pg 191 ...Even if (only) one creature is surprised, a surprise round occurs...
** We never do this **
PHB pg 267 has some meaningful text: "...if you fail your perception check to notice concealed enemies, you're surprised. Also if you're the only member of the party to fail your insight check to notice an NPC ally's traitorous intentions, you're surprised."

A creature can take one of the following during a surprise round; a minor action, a standard action or a move action. Creatures can also take immediate actions, opportunity actions, and free actions but no creature can use an Action Point. Note, surprised creatures cannot act at all during a surprise round.

Initiative is rolled as soon as one member of one side becomes aware of at least one member of the opposing side. Now, I'd say that hearing the enemies on the other side of a closed door isn't enough. I'm going to take the position that one creature has to be aware of one enemy AND have LOS to same. I could attempt to make a case for the aware creature to have both LOS and LOE, but that would be a harder case to make.

The text of the rules implies that the majority of encounters would have both sides becoming aware of each other at the same time; e.g. the traditional one group breaks down the door and both groups see each other at the same time (no surprise) even though one group (the guys breaking in the door) knew the other guys were in there and the guys in the room had no idea the uninvited guests were coming.

Discuss...

I disagree with the LOS requirement. Perception isn't just using sight. It's also about hearing, feeling, smelling, tremorsensing, etc. I would say if you know they are there you can gain a surprise round.

If your on one side of a door and enemies are trying to pound it down you clearly know they are coming in. My surprise action could be to teleport to the other side of the door, run down the corridor, Stealth, etc. A surprise round doesn't always have to be about attacking.

Note: If the enemy continues to not be aware, you can get full round actions after the surprise round. In the above case if the enemy can't get the door open and I'm stealthing (to be quiet), I would get my surprise action, and then full round actions as they continue to break down the door. An entire encounter can occur without them even knowing I was ever there. Of course the enemy would get full round actions as well. They just wouldn't know I was there.

Hmmm...if the enemy never becomes aware that you (Blade) are present, then you'd never have to roll initiative to start the encounter; meaning that you wouldn't have to have regular full round action turns at all? Just seeing if I understand you.

It would depend on the encounter. If the DM knows it takes a certain amount of damage to break the door, then we would have to go into Initiative mode. However, if I just stealthed and watched them go by then there may not be a battle.

Initiative is rolled whenever one opponent is aware of another. It doesn't say that "battle" starts at that point. It just says initiative is rolled.

..but doesn't a "battle" always start when initiative is rolled??

If I get a surprise round and I hide and don't engage then apparently it would still be round by round actions until I attacked, right.