Pathfinder increasing HD for planar binding effects

[Efrate]

Is there any way in pathfinder to increase the number of HD for planar binding effects? My diviner just hit 15 and I have 1 wizard bonus and one normal feat to spend, and was thinking of taking g. Planar binding as one of my spell as we were told we need to be prepared for a massive assault upon the lair of multiple liches and at least one half fiend dragon of bigness.

I want to get 20hd worth (so +2 HD) so I can get the big guns, wealth is not a concern, so if something exists as a prepublished item that is buyable I can get it.

[Psyren]

You mean like Augment Calling? (https://www.d20pfsrd.com/feats/general-feats/augment-calling/)

[Thunder999]

In addition to the mentioned augment calling there's the caller's feather (https://aonprd.com/MagicWondrousDisplay.aspx?FinalName=Caller%27s%20F eather) a 2000gp consumable that lets you summon 2 extra HD.

And if you're evil there's the blackfire adept prestige class which gets an extra 2HD at 3rd level, but only for a specific subtype of evil outsider, and the class loses a caster level at level 1 (and another two if you finish it) so it's not a great option even if you have time to retrain. (Though I suppose getting 18 HD at level 12 by combining all three could make for an interesting character)

[Efrate]

Perfect guys thanks. I know my feats and what I am going to be spending a bunch of cash on. Let's me get a solar for the final assault. Just got to grab a few cha item can only get +25 on the check currently.