Investigator covering almost all bases (8th level) needs another: Tankyness

[Spore]

Short summary of what my party provides:
- Ranger provides Stealth, Perception, Tracking and planning of our routes and general combat environments
- Paladin provides "Public Relations" and Healing
- Oracle of Time provides buffs and...well....further healing
- Oracle of Flames provides....uh....Fireballs? No seriously she has crippled her character beyond recognition (Melee with Str 12, Inflict Line of Spells with no Str and no Weapon Finesse as well as carefully handpicked spells which the player doesn't even know what they do).

My Investigator ... has to cover everything else. So far I've dipped into every Knowledge skill, have Spellcraft, Stealth, Alchemy (and try to use the skill for more than just creating stuff) as well as detecting and disabling traps, can offer Infusion Extracts and compete for highest DPR with the Archer Ranger and the Gunadin. Enough commitment, right?

There's just ONE small problem. I am the frontline in a party of 5. There was a very tanky built Dwarf Fighter who more or less quit the group (she simply doesn't show up and claims to have other obligations) and I fear my imminent death. I also feel that the DM scales the combat down since we have shown to struggle with CR equal encounters. It's a weird version of rocket tag in low levels: We throw out easy 100 dpr per round instantly but anything that survives that initial burst doesn't - uhm - help my complexion. Is there a way to help my tankyness? My current build so far:

Oni-Spawn Tiefling Investigator 8
Attributes 20/14/14/19/12/6

1. Armor of the Pit
3. Power Attack
3-Disc. Infusion
5. Master Craftsman (Alchemy)
5-Disc. Quick Study
7. Craft Wondrous Items
7-Disc. Sickening Offensive

I could push for Intimidate 9 ranks and Cornugon Smash for another -2 on enemy attacks. Do you think AC boosting, Displacement, Sickened and Shaken is enough to make myself survive a decent amount more? Do you think Inspired Intimidator is a smart choice or would you go for a diversified choice on the Investigator Talent. Like Studied Defense or Toppling Strike?

Are there Wondrous Items I can create to help me? Would you recommend getting Craft Magic Arms and Armor for something?

We will probably resort to using Draconic Reservoir (on me) plus Empowered Fireballs to deal with groups of weaker enemies so I can focus on debuffing or bringing down bigger opponents.

[Grod_The_Giant]

Cornugan Smash and Sickening Strike are a wonderful combination, and -4 to attacks and saves will certainly make everyone happy.

As for defenses, a few Extracts go a long way. Resinous Skin gives you DR/5 for a good long time; Ablative Barrier turns 5*CL damage into nonlethal, 5 at a time, and can be thrown up hours before a fight. Plus, you know, normal stuff like Barkskin and Blur.

[Geddy2112]

Second coragun smash+sickening strike

I would much rather have toppling strike than inspired intimidator- you only need a round or two of success with coragun smash if you are going to be wailing on the same target, and enemies immune to fear will become increasingly more common at higher levels.
A trip will hurt a melee attacker more and help your attacks connect. Studied defense is okay, but AC again becomes a losing man's game at higher levels. If you can trip them, its effectively a +4 AC to melee attacks they make, same you would get from studied defense at this level. However, them being prone gives you a +4 to attack, an AoO if they stand up, and if they stand up then there goes their full round attack.

I would prepare the long arm extract and use it to get extra reach, keeping enemies away from you and getting an Aoo if they get close. Displacement will be your bread and butter once you have enough 3rd level extracts to use it in every major fight. Don't forget heroism to boost saves.

A jingasa of the fortunate soldier is a dirt cheap head wondrous item. In addition to a luck bonus to AC, it can negate a crit per day.

[blayzenj]

Next level you should probably take the mutagen alchemist discovery. That would probably be the easiest thing you could do to increase tankyness.

[Spore]

Next level you should probably take the mutagen alchemist discovery. That would probably be the easiest thing you could do to increase tankyness.

I've switched from Mutagen Alchemist to Investigator as a product of my personal storyline (basically avoiding control of a CE Oni Spirit in the flask). If I used my mutagen now, this would increase mistrust ingame tenfold. It's like a crack junkie showing up with some kind of weird pipe that is "totally not a crack pipe".