Most survivable

What build(s) would be the most survivable? i.e. you have to work hard to actually die with this toon. I was thinking probably a defense heavy base powerset, slotted in some resists, with cardiac and rebirth radial. But i havent played around with it much, anyone got a better idea?

I mean overall against all damage types/positions, should have been more specific.

Definitely Stone/Dark. I have one that I built for survivability and he doesn't die... the problem is he doesn't do much damage either and that can get old too.

Would inv/dark be number 3 or is some other armor more resilient?

I know inv is best on s/l but from what I've seen it does quite good all around.

Besides Stone, there are a few tank options I think could make rather good tanks. Basically Invuln, WP for pure defensive. Electric and Dark can make tough tanks that have some offensive perks I think WP would ultimately be the strongest if you managed to build in enough defense.

A WP/DM tank, who capped S/L/E/N def, would be quite durable. I expect F/C will be pretty good as well in any build that gets the others to cap. So it will have good defense, plus good S/L resist, and a ton of hp/regen. This would be the toughest non stone tank IMO.

Invuln can also make a pretty strong tank, but it's somewhat weak vs non S/L. Not that it's weak, but not quite a good. With spiritual alpha available, it's easy to perma DP, and that makes it easy for Invuln to cap hp. So you have cap hp, can get good defense and huge S/L resist. But it wont have nearly as much regen as WP, so that is why I think it would come in behind WP.

Electric isn't considered a strong defensive set by many. I will admit that it isn't exactly. The advantages I see to electric is that it gives a strong base of resist, with only a small hole to toxic. The base resist on the Electric shields is generally higher then other powersets. A good electric build can get almost 80% S/L resist, capped energy, 55% resist to most everything else except toxic. Energize gives it an ok heal, plus some more regen, plus some end reduction. Once you add in SL from DM, and build for defenses with IOs, I think an Electric tank would could be very tough. Electric also has some nice offensive options with Lightning field and LR. The downside to Electric is that it doesn't have any +hp, so the health values are going to be a good chunk lower then WP or Invuln.

Dark has some advantages like electric, but the base value on the shields is lower, however it is stronger vs toxic and psi. It also has a defensive power, not huge, but a 2nd weave essentially, so would be easier to get defense numbers up to cap. It also has a better heal then electric. Main downside I see to Dark in the current game climate is it's a bit weak vs energy, and there is a lot of energy damage out there. But if you manage to get good energry def, even if it's not capped, i don't think it would be a major problem. It also lacks +hp like Electric.

So basically, most tank sets can be made tough with IOs. But generally if you want a really tough tank, you want some resists, and then you stack defense on top of that, then if you can, you get a 3rd type to stack on those, either HP or regen or a mix of both. So for pure toughness, I would say stone, then WP, then Invuln, then Dark, then Electric. DM is really the best attack set from a defensive standpoint. It has a great heal from Siphon Life, and has -to hit on it's attacks.

@OP
As you mentioned, anything defense capped with some resistances and I would also say regen to get your health up during the time the mob(s) miss.

The next thought would be if your doing 8/4 setting or fighting AVs or both. As an example to this my Robot FF Mastermind is defense capped along with the pets as well when buffed. But that is all I have going for me. I can solo 4/8 settings with the pets but I can't kill an AV. The AV also can't kill me. In the end we are at a stalemate both walking away annoyed. I have no debuffs to bring down his regen, defenses, resistances, nothing.

But on the other hand my Robot Traps Mastermind can do 4/8 settings and kill AVs. Of course I am not just relegated to just my Robot Trap Mastermind, all my Traps based characters can do just that.

So if your just looking to do 4/8 setting you need defenses just not to get hit much. You need some substantial DPS to clear out the mobs. Now it can be pure just massive DPS or moderate with the assistance of debuffs.

The issues come into play when your just doing average damage and even when defense capped and your regen on top of everything else is real low as well. Basically your not regenerating enough hit points back during the misses to be survive. I notice this type of an issue when I am being lazy and don't drop a triage beacon. I basically end up getting several hits sneak in and I end up poping 2 or 3 greens really fast to make up for the damage loss because I have learned if I just let it sit there I end up getting another hit which takes me.

I think that is another issue, since your fighting SO MANY mobs on a 4/8 setting sometimes you are subjected to that lucky chance to hit mechanism much more. End result 20 to 25 mobs trying to attack you and missing has a real good chance of having this activating with many mobs getting hits in all around the same time.

I also feel you need some type of damage mitigation in the form of some sort of aoe hold, immobilize, Knockdown or whatever. I think these types of powers extremely help in killing that massive hit streak as well. I know there are times again with my trap toons that the mobs just seem to go nuts sneaking hits in and it almost becomes a feeding frenzy in which I am the food. So as soon as I see something like this occurring I drop a poison traps with a lock down proc and immediately quells the room and gives me some breathing room to regroup. A usual combo for me with this is Poison traps followed by trip mine and some other AOE attack. If it doesn't kill off many mobs at least it sends them running for a bit.

I would say a stone tank for sure. I have alot of tanks and nothing can handle the damage a stoner can take. It will have the PSI hole, but you can only cover so much.

My Stone Tanker Electric is fun to play and does damage in groups that is for sure. Suffers on single targets as most attacks are aoe. My Stone tanks defense is ranging in the 60's to the mid 50's except for psi which is 20 atm. My resistences are capped at 90% on everything except psi which is only 3%

My Regen with rooted is 51 which I think is great. I also have focused accuracy so my to hits debuffs are over 86% and it has many other debuffs that hold around the 86% such as end debuff. This can make a hugh difference against certain enemies.

I have more end than I can handle so I never run out. Recharges in it mean I am almost level on recharge and remove the negative. My accuracy is great but you will have the - Damage aspect. My run speed is 30 mph so he is very fast in granite. My hitpoints are over 2000 and my heal recharges over 1600 hits and caps me at 3500+ when I use it.

It is a great fun build and if you wanted to cover your psi hole you can get barrier. I choose that and the heal so I can help my team out and I never need it anyway.

He is a beast and I could higher his stats if I wanted to lose some speed, but I like being fast and as you can see above, he can handle almost anything.

The one thing with the PSI hole that I do is switch to my other armours and then I am capped for alot of defenses in that form and my psi raise to the high 50's. So even that is covered.

I can also stand on monster island and have 10 of them around me and not feel a thing.

I have a wp/ss that is capped on all def. Regen is 71 and over 100 on a single target alone. He does alot more damage, but I know you want a pure tank.

He is pretty tough, but I notice on the resistance part how much that can play a role even with the high regen. He is also over 3000 for hitpoints, but does not have a heal :'[ But he is great fun and can really do some damage, plus is you get recharge you can footstomp galore!!!

The thing with the stoner though is they can become gods, but they are still demi-god even with no real expensive recipes.

Stone/Dark/Soul Tanker. Capped in nearly everything +Darkest Night gives -21% enemy damage. I'm sure someone will do the math for this but essentially you have 99% damage mitigation +rediculous regen. This build goes very far with alot of frankenslotting for +regen. With Siphon Life, Rooted, -Tohit and possibly Aid Self, your unbreakable.

A Stone/Dark Tank is indeed about as tough as you can get as far as pure mitigation goes. An Invul/Dark Tank with lots of recharge for perma-DP is also extremely tough, and a Dark/Dark Tank is tougher than either against psi users (and not a lot squishier vs others if heavily IOed).

However, there's something else that is even tougher: a perma-PA Illusion Controller. The only thing in the game that can kill one without the player screwing up is Hamidon... as long as you let the indestructible pets keep the aggro and don't miss refreshing them or Hasten (or AM if Ill/Rad) you are literally unkillable. Of course if you do screw up against a really hard spawn you're probably going to be eating floor before you realize what happened, so if you want something really forgiving play a Tanker. If you just want to be truly immortal as long as you don't make a mistake and able to solo pretty much any GM or AV (and have several billion inf to spare) go Illusion/Rad Controller.

I guess i dont quite understand PA, isnt there a decent amount of time when you are summoning the pets when they wont be out? So its really not possible to actually make them perma, and against some of the tougher stuff a few seconds is plenty of time to die.

Another for Stone/DM/BodyMastery (or w/e); sporting the following:
Spirit Core Paragon T4
Diamagnetic T3 100% -to-hit
Rebirth Radial Epiph T4
Seers T3
Void Radial Judge T4

My thoughs were to make the stone slab in "2001: A Space Odessey" that taunts everything by just standing there and being impervious. Its also a study in survivability. I'll look into Darkness mastery, tho. Thanks for that.