My wizard is fond of summoning or conjuring elementals and binding them using planar binding, keeping them around for a while. Even keeping them a day is awesome, because concentration is not required, although longer is better, at a 1000 a pop.
Whether the combination of summoning/conjuring and binding works isn't the question; the GM has ruled that it does. Likewise, the issue of concentration isn't the question; the GM has ruled in that regard also. (Hours of work on my part, they flip through a few items, and say "sure".)
The issue is . . . elementals are not enough. I need power, more power. Elementals are great, but they tend to have low saving throws, and it sucks having your elemental incapacitated or turned against you.
I want . . . a dragon.
Maybe an actual dragon might be a bit overkill, hopefully not literally. A draconic spirit would be great.
Specifically, I want to summon a draconic spirit and bind it, in a similar manner as planar binding, but planar binding won't work because it doesn't work on dragons. I've searched through the 5e compendium and not run across anything that really fits, but it's a big game and I'm hoping someone has an angle I haven't thought of.
I intend to research in-game, but our GM prefers if we bring solutions and information rather than coming at it empty-handed. The wizard is 14th level, with 15th looming over the horizon. If there's something that will work that is out of the wizard's reach, that's okay. I could conceivably beg, borrow, barter, or buy whatever it is. If there's any way at all, that opens the door. Okay, not any way at all, a way short of wish. That's a price too high.
For what it's worth, my wizard has already tried it -- the draconic spirit was happy enough to hang around for an hour, but planar binding did nothing (GM: does that work on dragons? Wizard: maybe? GM, looking at spell, "nope".)
In fact, I really am less interested in binding it than getting it to hang around more-or-less voluntarily, so if actual coercion weren't necessary that would be a bonus.
So, my question is this: how can I extend the stay of a summoned draconic spirit in a way similar to planar binding, recognizing that planar binding won't work on dragons?