Make the Ethereal spells grant Invisibility.

[Laurk]

Well in my opinion, Sanctuary should break if you do anything hostile, including preparing to attack someone. So blatant attack buffs, summoning monsters and of course, hostile attack or coersive mind spells should break it. Basically defensive buffs, healing, restoratives, and that sort should be fine. Somehow I don't think the God's wouldnt be able to figure out your preparing to smash someone's face as you cast divine might and light your hammer on fire.

[Kitsunestume]

Good day all,
Good debate going on here, figured I might add a few comments and data.
Firstly, I fully agree with Manu on his statement:

The root of the issue is whether or not "buffing" is considered an offensive act.

The problem does seem to revolve around the consideration of offensive or hostile.
Unfortunately, the syntax of the spells in P&P all seem to use the word "Attack", specifically causing direct harm to another being. The NWN2 wiki indicates that these spells use the term Hostile in addition to the standard statements about attacking. D20SRD Invisibility seems to have the most robust definition.

Invisibility:
The spell ends if the subject attacks any creature. For purposes of this spell, an attack includes any spell targeting a foe or whose area or effect includes a foe. (Exactly who is a foe depends on the invisible character’s perceptions.) Actions directed at unattended objects do not break the spell. Causing harm indirectly is not an attack. Thus, an invisible being can open doors, talk, eat, climb stairs, summon monsters and have them attack, cut the ropes holding a rope bridge while enemies are on the bridge, remotely trigger traps, open a portcullis to release attack dogs, and so forth. If the subject attacks directly, however, it immediately becomes visible along with all its gear. Spells such as bless that specifically affect allies but not foes are not attacks for this purpose, even when they include foes in their area.
Sanctuary:
The subject cannot attack without breaking the spell but may use nonattack spells or otherwise act.
Ethereal Jaunt/Etherealness:
Does not apply for P&P

Invisibility:
The spell effect ends if the creature makes an attack or casts a spell.
Sanctuary:
Attacking, casting a spell, or performing another hostile action cancels the spell.
Ethereal Jaunt/Etherealness:
Attacking or performing a hostile action will make the etherealness vanish.

Bringing it back to the rest of Manu's post:

In Sundren, "Buffing" or preparing for battle is considered a hostile action. Should a possible opponent begin buffing, you may immediately flag them hostile and begin PvP, bypassing any need for making them aware of impending attacks.

This is why any spells cast while in Etherealness, if you are toggled hostile, should immediately pull you out of the spell.

Cheers!

This is a excellent point. Per the NWN2 and Sundren interpretation, if you know your going to go into a dungeon and fight a bunch of statically located mobs, and preparations that assist in the progress of that goal are intrinsitcally linked to a hostile intent. They arn't going to wander out of that dungeon; you are knowingly going in there to ruin someone's day, and your mage-armor beforehand is going to help you do it better.
In counterpoint, if you are sitting somewhere where a 'hostile' force may occur, say the same dungeon and your mortal enemy comes stalking through looking for you, it becomes a matter of being stuck between a rock and a sharp-sword. You may not know if they can see through your spell but just want to get out. Suddenly casting mage-armor becomes defensive: you just want to survive long enough to escape.
It gets particularly fuzzy in the event your fighting someone just to stay alive: attacks are offensive, self-defense is defensive.
Depending on the viewpoint of the individual, 'hostile' can change drastically, as mentioned in the P&P invisibility description.

Food for thought.

While I easily support Laurk's supported name-change(after all, Etherealness/EJ just applies a Sanctuary Effect), I would personally be averse to changing the current mechanics based off an ill-conceived generalization of rules-translations from one system to another.

Cheers,
Kit

[Laurk]

One thing to consider, invisability is "primarily" arcane. You could work with loopholes in arcane casting, and thus preparing to attack would not be the same as a "hostile action."

You can't get away with that sort of loophole with the Gods, because they know exactly what you're doing. In a PnP campaign, I would never let someone in a sanctuary effect make preperations to attack someone/thing because it is clearly hostile intent and their god would say: Nope. The best way to to make this a mechanical automated thing would be to allow defensive buffs, but never offensive ones during Sanctuary effects, but leave invis alone.

Trouble is, Arcane casters should have Ethrealness, and divine should have Sanctuary. So in the end... just leave it be and give people the option to RP it as Sanctuary or Ethrealness(with lame drawbacks) and call it a day.

Also, Kitsunstume, the PnP description for Sanctuary says this:

Any opponent attempting to strike or otherwise directly attack the warded creature, even with a targeted spell, must attempt a Will save. If the save succeeds, the opponent can attack normally and is unaffected by that casting of the spell. If the save fails, the opponent can’t follow through with the attack, that part of its action is lost, and it can’t directly attack the warded creature for the duration of the spell. Those not attempting to attack the subject remain unaffected. This spell does not prevent the warded creature from being attacked or affected by area or effect spells. The subject cannot attack without breaking the spell but may use nonattack spells or otherwise act.

That's a bit differant than the NWN2 descrition which says they can't cast spells. Esspecially given that in practice, you "can" cast spell in sanctuary, just not hostile ones. I would defer to the PnP version which at least doesn't contradict how the spell actually works in game. I think you could read Sanctuary off the NWN2 wiki as talking about 'hostile" spells, but it doesn't make that clear.

[Starrizer]

Again - choose your battles. If your going to fight a spell caster knowingly - you've aceess through rp of both sides via PCs to ask what to expect. Same goes opposite - if the enemy finds you he probably already has his buffs ready as he came for you. Sounds like you may want to "restrict" etheral image to being a powerful spell that you may learn through scrolls - only attainable through rare mob or perhaps DM authroization (I.e. Your a respnsible player and as a high ranking member of the appropiate faction you request such teachings.)

[Doubtful]

I wouldn't confuse Hostile spells with hostile actions in PvP.

Hostile spells are those that target a foe and cause him or her harm.

Hostile actions in PvP sense are actions those are seen to instigate a fight (it may help if you consider these as aggressive acts). These could be taking a swing, drawing a sword or beginning to summon up arcane/divine energies.

It doesn't need a hostile spell to be a hostile act.

[Kitsunestume]

Also, Kitsunstume, the PnP description for Sanctuary says this:
[...]
That's a bit differant than the NWN2 descrition which says they can't cast spells. Esspecially given that in practice, you "can" cast spell in sanctuary, just not hostile ones. I would defer to the PnP version which at least doesn't contradict how the spell actually works in game. I think you could read Sanctuary off the NWN2 wiki as talking about 'hostile" spells, but it doesn't make that clear.

Laurk,
I did indeed notice.
If you look, I had included the sentence you chose to bold in the section derived from P&P, to make exactly that point. Invisibility describes most completely what the rules by the book might describe as attack, hence it's slightly higher priority in my post.
Also, once you start to consider intent, how far ahead do you look? Healing a fighter so he can get up and smack some more people in defense of a temple is beneficent (to the fighter) in the short term, offensive (to whoever they can now hit MORE) in the overall combat and both beneficial for your deity and offensive to others in the long-term.
The wording chosen for NWN2 spell descriptions was significantly less considered than those of P&P, leaving the definition of 'hostile' up to the two descriptions Doubt has outlined: the difference between a hostile action as it refers to direct combat and a hostile act as it refers to social dynamics.

Also, making tables of what is and isn't an 'hostile' spell would be quite an task, and require every spell have another boolean. Not likely a complicated problem, but also not an insignificant undertaking, requireing a fair amount of consideration. Example: Bull's Strength helps you hit stuff harder, or haul that fallen comrade out past the things who would love your hide on their chair. Hostile? Debatable. Game-engines suck at this. Hence our awesome DM staff.

Although now I have an amusing mental image of someone's invisibility popping because they wandered into the wrong neighborhood wearing the wrong colour.
Or popping because they cast invisibility with the intent to be aggressive.

[prismaticcrow]

The closest answer I could find was from the paizo forums (where Pathfinder comes from). The general agreement seems to be that summoning monsters and buffing doesn't break Sanctuary, but spells that affect your enemies, like fireball or even grease, are considered to "attack" the target and break the effect.

I believe the 3.5 Player's Guide gives an example of the use of Sanctuary while summoning a monster, but I can't find it, so I won't state it as fact.

The bottom line is, though, is that intentions are not something the Nwn2 game can judge, thus we must be totally and coldly logical about how it works. I say either make the spell grant invisibility to help enforce the "vanishing into the ether part" or rename the spell "Greater Sanctuary", like suggested and call it a day.