Ideal Phantom Steal Skill set-up?

I've heard that any mage attacks still count as physical damage when used by a Phantom. Can't confirm though; like you I stuck to buffs.

Chain Lightning does indeed bypass Super WDEF Up and complete physical resistance (i.e. Arkarium snakes). Unfortunately it's not very powerful; Ark is really the only place it's useful.

My personal setup was:
1) Magic Guard, Haste
2) Dark Clarity (stacks with everything), Hyper Body, Heal, Threaten
3) Magic Crash, Combo, Dispel
4) Rapid Fire, SE/Res

I believe Heal is based off your INT amount, but mine is high enough that it heals almost everyone in one or two heals, which is enough. Now that Rage stacks with att potions I may take that over DC, because it's a party buff and casts much faster. Sometimes I carry Chain Lightning in the 4th job slot for ark and laziness, I almost always use Rapid Fire.

Mine.

1) MG, Haste, Dark Sight, Iron Body
2) Dark Clarity (because it stacks with everything, like Aflac said), Heal, Threaten, HB (I almost don't use HB at all)
3) HS, Combo, Concentration (because it stacks with everything else too)
4) RF, Parrottargetting

Heal depends on MA, as far as I remember. It gave me quite a big increase in heal amount before and after those event buffs that +WA/MA.

Parrottargetting is for bossing e.g. when I decide to do a Krexel for lolz. It's not bad in terms of damage increase, just don't DC yourself when changing skills!! But I'm not sure if Parrottargetting's effect is felt by other players...

In a party game, Crash is way more important than other stuff, so that should be in one of your slots. HB would be lovely (if you have friends hitting cap... Rage would be pointless), and AB/SE is nice too (I'd use AB), but Ress would be excellent. 1st job skills are just lolz, so use MG for your own survivability. With MG you can take bigger hits quite readily, especially with HB -- Jr. Boogie familiar ftw.

Hadriel

I read some stuff Heal is lackluster on Phantom. Is that simply not the case and it actually heals about as well as a Bishop using it?

It heals about as well as it would on a Bishop with 70 int (or whatever your Phantom has). ~400 hp for my level 7x Phantom. I think it is entirely int-based, though I didn't find any m.atk weapons I could test otherwise for.

Toss in a magic potion (those +5ma for 3 min that can be bought from most pot NPCs). My lvl. 14x phantom heals for 1k-1.5k each time... plenty enough for me.

Hadriel