How to get better Constitution

[SpicyBoi_Nezu]

I had the concept of building an unkillable mage/tank by using the Lost Tradition feat to allow him to use his Constitution instead of his Charisma/Wisdom/Intelligence for his spellcasting. Because of the level 5 ability of the Abjurant Champion class, taking levels in martial classes will not have as big of an impact on CL.

I still need to research specific spells, as well as a suitable base Arcane Spell-casting class, but I need to know the best way to make this happen.

[noob]

shapechange in a shambling mound.
http://www.d20srd.org/srd/monsters/shamblingMound.htm
Then hit yourself with a lightning spoon over and over.

[Eldariel]

I had the concept of building an unkillable mage/tank by using the Lost Tradition feat to allow him to use his Constitution instead of his Charisma/Wisdom/Intelligence for his spellcasting. Because of the level 5 ability of the Abjurant Champion class, taking levels in martial classes will not have as big of an impact on CL.

I still need to research specific spells, as well as a suitable base Arcane Spell-casting class, but I need to know the best way to make this happen.

Well, Con is easily pumped via. a number of means. As mentioned, Polymorph-effects are of course top of the line but that particular combination might be a bit too much since it's almost infinite. Most of the spells I mentioned in the Str thread work for Con as well; notably Draconic Polymorph, Bite of the Werebear (or WereX), Giant Size/Righteous Might.

[Biggus]

Other spells that boost Con:

Aura of Vitality (morale)
Holy/ Infernal Transformation (sacred/ profane)
Greater Visage of the Deity (untyped)

All are Transmutation so can be boosted a further +2 with the Ability Enhancer feat.

[Maat Mons]

You could also do the reverse: True Mind Switch with a high-Con creature, Polymorph into a human, then cast Strength of the True form.

[Eldariel]

You could also do the reverse: True Mind Switch with a high-Con creature, Polymorph into a human, then cast Strength of the True form.

Magic Jar chain (Magic Jar into X, Magic Jar out of X and remain in your Jar, have an underling move the first Jar out of the range of the spell and break it thus killing the spirit of the first creature and ending the first instance of the spell - as you're in another Magic Jar, not the Magic Jar referred to by the first spell, you'll live and with the new body as your host) allows an earlier and easier access to it for an arcane caster. Obviously, one of the huge advantages of this is that there's no limit to what Magic Jar can take over. Feel free to be the Tarrasque and start up from there.

[Anthrowhale]

You might instead use Faerie Mysteries Initiate to retain an Int focus with significant hitpoints.

[RNightstalker]

Chosen of Mystra gain a +10 enhancement bonus