I do have a question for Dandu. PCs in any of the games I've ever played in have only ever used Planar Binding spells VERY sparingly. And usually things end up bad.
That's why I tend to bind Good characters. They tend to backstab you less than Evil ones.
How do you use Planar Binding in combat? It takes 10 minutes to cast.
Why in the Nine Hells of Baator would you assume that I cast it in combat? Given that the called creature can stay for a very long period of time, it makes the most sense to cast it in out of combat beforehand.
Either that or lock up your enemy in a Resilient Sphere first. That should last long enough.
First they get a save, then they get a couple of different ways to try and escape the magic circle. Then you have to beat them with a charisma check, or bribe them with a DM determined something, which can be ugly for anything other than sorcerers.
How fortunate that a sorcerer, who Binds creatures beforehand, has enough time to try until something fails the save and negotiate.
A wizard could do it too with a casting of Eagle's Splendor and a Circlet of Charisma.
In the case of making a critter use divination magic, you have to worry about them out and out lying to you, or 'misinterpreting' the message, on top of the already present chance of divinations failing.
There are several ways of doing this. The agreement could ask the Imp or Quasit to relate to you literally what was said, in which case they would be compelled to follow if you word it right. You can have someone standing by with a high Sense Motive check like the party rogue or bard. You can Diplomacy or Intimidate the bugger into relaying things truthfully. You can Charm, Dominate, Zone of Truth, or whatever the creature to ensure it does not lie.
The list can go on.
Then you have to deal with the possibility of retaliation, or whatever you summoned getting his powerful outsider buddies to pay you a visit. Especially if you are doing it regularly.
Oh yes, because Imps and Quasits regularly have the ear of powerful Balors and whatnot...
Part of my MO for binding things is to either bind weak evil creatures that are really unlikely to have powerful allies, or bind Good creatures that I can work out an agreement with since we are on the same side and are likely to support each other's efforts at promoting good in the world. After all, one of the defining aspects of the Good alignment is that good people work together, unlike Evil creatures which have a tendency to backstab and betray each other for selfish goals.
"Good" implies altruism, respect for life, and a concern for the dignity of sentient beings. Good characters make personal sacrifices to help others.
"Evil" implies hurting, oppressing, and killing others. Some evil creatures simply have no compassion for others and kill without qualms if doing so is convenient. Others actively pursue evil, killing for sport or out of duty to some evil deity or master.
Good creatures, if you explain your reason for calling them well and politely, are also less likely to attack you than evil creatures if they escape.
Ideally, I would bind someone that I had established relationships beforehand, since by the time I get Planar Binding, I'll have gone on at least one planar adventure. If not, there's the fact that I try to establish relations with churches of Good deities, and I can ask them to help recommend an ally.
Is there an assumption that the mage and his party should just hunker down around a calling circle in their house? Then cast the spell over and over again, possibly killing several escaped creatures until something fails its save? I've never had a DM that would let that happen on an even remotely occasional basis.
That you do not have DMs which allow this is proof that Planar Binding is overpowered as written. If we accept that no sane DM would allow Planar Binding abuse (or other broken spells) by houserules, we still get a situation where spellcasters can cover several roles in the party; damage, control, buffing, debuffing, and utility.
If we're going with what a "reasonable" DM would allow, replace Magic Circle with Haste, Dimension Anchor with Arcane Eye, and Planar Binding with Contingency. You still get a character that's more powerful and versatile than someone who is mostly restricted to hitting something with a sharp stick.
I see that using the magic circle reduces the chances it will break free, and makes the charisma check harder. But also requires another 10+ minutes casting time, plus use of a dimensional anchor, plus the silver spell component.
Look closely. I also have Dimension Anchor in my list of spells known. Also, note the material component reads:
Arcane Material Component
A little powdered silver with which you trace a 3-foot diameter circle on the floor (or ground) around the creature to be warded.
No cost listed. The silver is to insignificant to drain your coffers.
The part where the circle is easily broken though would worry me...I've watched Supernatural, lol. Oh look...the leaves I happened to have in my pocket accidentally blew onto the glyph. Oops!
That is why my sorceresses perform the Planar Binding in a closed room while naked.
Also...do divination spells even work if used by a creature trapped by the circle? Since their spells specifically can't go beyond the circle? How do you contact another plane when you can't even contact the space 10 feet away.
That seems to be the exact opposite of what the
Magic Circle spell says.
The creature cannot reach across the magic circle, but its ranged attacks (ranged weapons, spells, magical abilities, and the like) can.