The Ogre Mage can cast Invisibility at will as a spell-like ability. Can he cast it on his allies?
I'm looking mostly for errata or precedent (FAQ/Sage/Module/Whatever) about whether the Ogre Mage's invisibility has been "corrected" to be invisibility (self only), because in AD&D they could only become invisible themselves.
Also, does this apply to Gaseous Form as well (though that has a limit 1/day)?
Yes. I never thought of that usage for them before, but I would have to say yes. If you look at other entries like the Bone Devil (Osyluth) under special abilities they are sometimes noted as "Invisibility (self only)". The Ogre Magi has no such notation, so it will work just like the spell definition I believe - both Invisibility and Gaseous Form allow targets like other creatures, so he could use these abilities on allies, not just himself.
Good question, if I am right about my answer, I never thought about the Ogre Magi using those abilities that way.
Just for historical reference, the AD&D 2.0 Ogre Mage from Monstrous Manual read under Combat: "can perform the following feats of magic: fly (for 12 turns), become invisible" and also "assume gaseous form" so these abilities were definitely personal in previous editions. Also of note, they picked up Spell Resistance: 19 in the 3.5 edition, which is pretty significant.
The 2.0 MM Edition said they could do 'Darkness (10' radius)' - in 2.0 Darkness was normally a 15' radius even the actual wizard spell name had the radius in the name. It also was cast at Range: 10 yards/level and was pretty much a total blackout in the area of effect.
In 3.5 edition, Darkness is a Range: Touch, Target: Object Touched
"This spell causes an object to radiate shadowy illumination out to a 20-foot radius. All creatures in the area gain concealment (20% miss chance). Even creatures that can normally see in such conditions (such as with darkvision or low-light vision) have the miss chance in an area shrouded in magical darkness."
So one can imagine the Ogre Mage, while invisible, quietly moving through an area and touching torch sconces 'putting the lights out' before a big assault begins.
Both invisibility and gaseous form have “Range: Touch” and “Target: One creature” (invisibility can also be used as “Range: Personal” and “Target: You” or “Range: Touch” and “Target: One object”), and being cast as a spell-like ability does not change any of the parameters of the spell aside from the Components (which spell-like abilities do not have) and being immune to/useless for counterspelling.
From the SRD, Special Abilities:
Spell-Like Abilities (Sp)
Usually, a spell-like ability works just like the spell of that name. A few spell-like abilities are unique; these are explained in the text where they are described.
A spell-like ability has no verbal, somatic, or material component, nor does it require a focus or have an XP cost. The user activates it mentally. Armor never affects a spell-like ability’s use, even if the ability resembles an arcane spell with a somatic component.
A spell-like ability takes the same amount of time to complete as the spell that it mimics (usually 1 standard action) unless otherwise stated. Spell-like abilities cannot be used to counterspell, nor can they be counterspelled. In all other ways, a spell-like ability functions just like a spell
Emphases mine.
Many creatures have modified spell-like abilities that do not behave just like the spell, but such exceptions must be noted specifically in that creature’s entry. Compare, for example, the very-common spell-like ability “greater teleport (self only),” found on many Outsiders.
