Non-Class based ways to increase Effective Druid Level?

[Vaz]

I am currently planning a Level 20 Character for a BBEG; Druid 9/Beastmaster 1/Ardent 5/Black Dog 3, with the Natural Bond Feat and Wild Cohort. I currently have a Colossal and a Gargantuan Monstrous Centipede as it's animal companions (one through Druid, one through Monstrous Centipede); the Colossal Centipede is counted as if my Druid level was 1, the Gargantuan as if I were Druid 3. I'd rather not take further druid or Beastmaster advancement in place of the Ardent; I have Practised Manifester for an Ardent, and an Ardent 5 with Practised Manifester can cast Powers with a PP total of 9 or less.

My feat selection is Wild Cohort, Natural Bond, Practised Manifester, and Metamorphic Transfer. This gives me 3 feats to use; is there any way I can boost my effective Druid level to 6 (+5 and +3 respectively), through the use of items, feats, skills, spells, etc? 3rd party, Dungeon or Dragon are not allowed, although Dragon Compendium is.

I'd really like to do this without custom making an Item; as the other team all have some form of Animal Cohort (including one going towards an Ubermount through a Wizard/Druid Hierophant). If there is one within the game, there's no real problem, as my players are free to use it already; but if not, and custom houseruling (I play with what's good enough for me, is good enough for my players, and houseruling "his armour crumbles to ash on his death" is not my style of DM'ing and I do not wish to start) is in order, I don't really want to consider the consequences, my players are learning to break things (such as the level 11 Arcane Hierophant with the abilities of an 11th level AC and 11th level Familiar wrapped into one).

[Ellrin]

If you're not averse to using PF feats, there's Boon Companion (http://www.d20pfsrd.com/feats/general-feats/boon-companion), which is effectively Practised Spellcaster/Manifester except with your effective druid level for your animal companion (+4, to a max of your character level).


such as the level 11 Arcane Hierophant with the abilities of an 11th level AC and 11th level Familiar wrapped into one

...wait, how's that work?

EDIT:
You could also homebrew a druid/psionic theurge class that's effectively arcane hierophant but with psionics instead of arcane magic. Since psionics doesn't have the problem with armor that arcane magic does, and you don't have a familiar, change companion familiar to just increase companion progression, drop ignore ASF. Maybe to make up for it, allow a slower mantle progression since you're going ardent.

[Vaz]

Practised Spellcaster, Natural Bond, Arcane Hierophant combines both AC and Familiar together. Practised Spellcaster and Natural Bond off-set the penalty for taking 3 levels in another class to qualify for Arcane Hierophant.

Sadly, no, it's 3.5, with 3.X included pretty much verbatim (apart from a direct clash in wordings, or when a book uses an outdated version of an updated one; i.e Damage Reduction from 3.0 to 3.5), so no Pathfinder, I don't particularly want to spring Pathfinder on them, due to the whole "what works for me" thing.

However, Natural Bond does exactly the same thing for myself, although only +3 rather than +4. That +3 is what allows me to qualify for a Colossal Monstrous Centipede at Druid 9/Beastmaster 1/Ardent 5/Black Dog 1 (advancing Black Dog by ECL20).

[Ellrin]

Wait, practised spellcaster advances familiar level, too?

Anyway, you could potentially houserule natural bond into functioning like boon companion for an additional +1--it won't make an effective difference for your player who has it (since it would only function up to a maximum of your character level), and I'm sure he'd appreciate it once the Arcane Hierophant gravy train runs out (though since it'd only be an additional +1, it would hardly be a significant extra worry for you--no more than it's been already).

If you do that and use that homebrew idea for a Psionic Hierophant (working title), you could conceivably get...

Druid 3/Ardent 3/Beast Master 1/Psionic Hierophant 8/Black Dog 1

What book is Black Dog from? I don't remember ever hearing of it before. And just out of curiosity, what's the appeal of the Beast Master dip? The only thing you get out of it that you wouldn't get from another level of druid is the +2 Ref and full BAB, and you lose a level of spellcasting and wild shaping. Alternatively, you could go another level of PH, lose the wild empathy, BAB, and Fort and Ref, and gain a level of both ardent, druid, and wildshape (and maybe an extra mantle, depending on if you decide to give mantle progression to PH and how often).

[Tulya]

Wait, practised spellcaster advances familiar level, too?

It doesn't, nor do I see anything in the Companion Familiar ability that would cause it to. Companion familiar retains familiar traits progression based on class levels, not caster level.

[Ellrin]

Yeah. I don't see where a Dru3/Wiz3/AH5 is getting a companion familiar with 11th level familiar traits with the feats listed.

[Vaz]

So, my DM reading comprehension aside...

Anyone care to answer the actual question?