How to get more HD outsiders using Summon Planar Ally

[Iwasforger03]

I'd like to ask the playground what's available for increasing the available HD with the spell Summon Planar Ally and its lesser/greater versions.

This is related to a project i'm working on involving clerics and persistent spell/divine meta magic and the thread regarding PS i posted a moment ago.

Basically: Looking at a couple theory builds for making a warrior/caster gish that can hold off an army of by himself, and the various options available to him to help him do that. Summons present an opportunity to gain assistance and buy time for rest, healing, etc. They can also increase the character's effectiveness. I noticed that Solar's are listed in the d20pfsrd's list of outsiders, and wondered if there was a way to increase the threshhold of 18HD up to 22HD so that a Solar could be summoned, though ways to increase it with lesser and normal versions are also helpful because even just getting a 13 or 14 HD summon out of a regular planar ally spell is really useful.

[golem1972]

Malcontents 8 will bump the hd cap on your planar ally / planar binding spells by 2. Implore from dragon magazine #336 calls up to 24 hd. I don't believe they stack.

[Iwasforger03]

Where's Malcontents?

[Rebel7284]

http://dndtools.eu/classes/malconvoker/

Also look into Reserves of Strength feat.

[Iwasforger03]

Reserves of str won't help, the HD aren't based on my caster level. useful for summon monster though.

[golem1972]

Malconvoker not malcontents, stupid auto-correct.

Still trying to finagle my way into a bard based malconvoker. Requires homebrewing to make it work.