Wanted to build nasus as a meat shield due to the exhaust + wither + his ult. In team battles i think he would do pretty dam good.

Last game i played i managed to get guardian angel + force of nature and started frozen heart before they surrendered causing me to get 60% nullified damage for resist and armor by 20 mins.

What I was thinking was:

Guardian angel +force of nature.

Then if there is more AD I would go:

Guardian angel + Force of nature + thornmail x2 + Frozen heart + force of nature

Or if there is more ap/ a strong ap carry like veigar:

Guardian angel + Force of nature x3 + thornmail + Banshees veil

What do you guys think?

TLDR:

Want to get so much dmg resist im invincible so my team can stand behind me and kill them leaving me with 0/0/30

IMO you should build another character like that better built for tanking. Nasus (again, this is my opinion) should have at least some damage items because he does amazing damage when farmed right and having items to compliment that will make him really perform.

How about including a trinity and atmas in your build? That could still leave you tanky as you are yet able to dish out nice damage.

Oh and another thing, I don't recommend stacking FoN's or Thornmail.

After you have all tank items, the enemy will laugh at how your Q's still only do ~200 damage after all their armor is factored in. Nasus needs to be built tanky, but he also needs to be a threat in fights.

Frozen Heart is core on Nasus because of the CDR, Armor, and aura. TriForce is also considered by some to be core, but I think that it can be delayed (heavily at times) if you need other items first (although Sheen and Phage are awesome). Last Whisper and Bloodthirster are both endgame situational items because a tanky Nasus with a farmed Q can gain back tons of health. Guardian Angel is always a good item to consider at any point in the game. Atmog's works well on him. Based on the bracket and game progression, Thornmail could be considered. A guide I read said to follow a progression like this: Merc (Tabi), Glacial Shroud, TriForce, FH, GA, Mog, Atma's.

His main threat is the ability to Q spam targets, so if you don't supplement your damage at all, then they will build defense faster than you can farm your Q and it will deal less meaningful damage as the game progresses, to an extent.

Idk I just think if there are extreme dps champions out there that work because tanks take the damage for them so they can slip in and destroy then a extreme tank champion should also be able to work so i can disarm and hold back the damage in my lane while my dps partner finishes them off allowing us to push very easily.

The same would go for team fights, i would charge in first and get the fury of everyone, using my heal and ult plus my resistances to be able to last 30-60 seconds while my team threw out their combos dealing huge damage to the enemy team and killing 2 or 3 of them before i die. leaving the rest to get picked off or run away as fast as possible.

Nobody will attack a Nasus without a farmed Q + max CDR. How do you plan on "taking damage for" your carries?

This used to be one of my strategies with Mundo. Build to be invincible and run screaming into enemies, taking the brunt of the CC and damage. It was awesome. Then I started playing people that are actually decent, and they would ignore me and kill my squishies. Unless you're a character with great control over others (which Nasus doesn't really have), this isn't viable beyond new or bad players.

haha literally lol'd at your "run screaming into enemies"

But yes I see your point, I suppose they would target me at first, then seeing my damage resistance just ignore me while i pounded on them pointlessly with my fists.

get sheen. Leave sheen as sheen don't upgrade till late
then biuld your meat shield
People may not target you so try going for aura items if they don't