For this part all you need is to make a Wizard (yes i know the low hp but hear me out)
Now max out Dexterity, go either human or half-elf to get that sweet 16 Dex (or an elf if you want to go above and beyond and get that 17 Dex)
For one of your spells get Mage armor and thats it

Now simply cast mage armor on yourself and now you have a 16 AC
Very high AC = Harder to hit
Harder to hit = Less hits taken
Less hits taken = No Death

Therfore Very high AC = No Death

Clerics have Shield of Faith, which adds a +2 to anyones AC

Have the Cleric cast it on you for that crisp 18 AC (good luck hitting that)

And if you want to go even further:
Get a potion or a spell that gives you haste. Haste gives yet another +2 AC (Beware the stun afterwards)

Now you have 20 AC, may even the gods fear your naked body (because keep in mind, Mage armor only works without any armor)