Part of the problem with phasing-out creatures is that, in PnP Dungeons and Dragons, there are many ways to counter them, while in DDO they're forbidden. For example: remember the Ogre Magi that have a habit of phasing out when their health drops below a certain point? In PnP, that's supposed to be an Invisibility spell. So someone with See Invisible, and especially True Seeing, should be able to spot, attack, and kill them if they want to. Yet, it's not that way in DDO. Someone coding this behavior either forgot about possible counters to this ability, or did it on purpose, wanting players to patiently wait until the creature is willing to come back and get killed (so what if players can see invisible creatures? they are invisible to them anyway!). At least they aren't allowed to attack in that state, otherwise it would be 'patiently wait until the invisible and completely invulnerable creature finishes killing you...' (btw, this reminds me of the djinni ).
With creatures like Phasing Spiders and most kinds of ghosts it is a different matter. They go to the Ethereal plane where they are completely invulnerable to any attacks aimed at them from our 'normal' plane, even (most) magic attacks. So yes, being immune to our attacks is justified. However, even if they DO enter Ethereal plane, they are still detected by See Invisible and True Seeing! But can we see them in DDO? Phase Spiders are visible, but not ghosts...
I can think of some ways this could be brought more in line with PnP behavior, and less frustrating to counter. Those are only suggestions, and since they would require rewriting the current code for phasing, I don't see them getting live anytime soon (if this ever gets to live at all...).
Bugbear Assasins
Depending on what is the nature of their phasing-out:
- If it's supposed to be an Invisibility spell, then a See Invisible or True Seeing spell should reveal their location.
- If it's something alike to 'throw a smoke bomb and sneak away' then they should be handled like a normal sneaking enemy (and Spot/Listen should reveal their location).
Either way, it should be possible to attack and target them after noticing.
Ogre Magi
Location revealed by See Invisible and True Seeing, and it should be possible to attack and target them (they're supposed to be using Invisibility spell to vanish).
Phase Spiders
While phased-out, they are handled similarly to Incorporeal creatures (no damage on hit), but hitting brings up an 'Ethereal' message instead of 'Incorporeal', magic weapons have a 0% chance to work (not 50%), and Ghost Touch weapon property is ignored. They are unaffected by any spell being cast on them, and any area spell effect they enter (but spells and effects, magical or not, that have already been put on them don't cease to function).
Exceptions
Ethereal and similar item effects make the weapon able to affect a phased-out Phase Spider normally, without the Ethereal message. Force spells affect them normally (and while not dealing force damage, Blade Barrier should affect them too, because the blades are made out of magical force).
Wraiths, Spectres, Shades, etc.
While phased-out, See Invisible and True Seeing now makes them visible. Weapons that affect phased-out Phase Spiders should affect phased-out ghosts too.
Scorpions
Add the Earthquake spell - casting it in an area where a scorpion has buried will force it to make a Fortitude (or Will) save, failed save means it is forced out to the surface and dazed until hit (also add an item everybody can use with a few charges of this spell).
Except for that, I'm all for giving phase abilities some cooldown to make them not spammable, and less frustrating to fight for everyone.