As my ELO progresses forward, I realize more and more of my games reach the "end" or "late" game stage where the outcome can be decided by a single teamfight, BD, building kill, Nashor, etc. As a physical DPS hero (carry here on out), how do you prepare for this stage of the game?

Between levels 14-16 you've probably finished your core, if you're having a decent game, leaving you with 2-3 item slots left to fill. How would you fill these and why? Obviously there's itemization differences between the carries and the situations you face, feel free to be as specific (pertaining to one champ and/or game situation/enemy composition) or as general as you would like.

I haven't had a whole lot of success in the end-game department as a carry, I can avoid death and deal massive amounts of damage fairly well, but I'm wondering if my lack of itemization knowledge is dulling my edge. I normally play a tank and so am unfamiliar with the different strategies people employ for carrying in the last stage of play. Do you shore up your defenses or become an utter glass cannon? Health stacking, lifesteal, or Guardians? I appreciate any and all responses received, thank you for your input.

Give Leviathan a shot, it's a cheap source of health-pool if you're careful. I play ranged-dps mostly so I get out of team fights alive. Other than boots, it's the only defensive item I get (though I'd get Banshee instead of Levi when their team comp warrants it).

Banshees is thee best in most cases.

You just have to do what's needed to stay effective. That can mean a lot of things, though, and doesn't necessarily mean staying alive.

You might tank up with a mallet, levi, quicksilver, or veil. You might select some hybrid gear that gives you some tanking to go with your damage like wit's end or phantom dancer. You might decide to spam wards, you might also decide that face smashing damage is just more useful.

Well, this is what I do for trist but it applies to all carries I guess:

I'd get banshee's and atma's against mages and DPS respectively. Switch banshee's with frozen mallet is casters aren't that much of an issue and you need to kite some DPS. If they have lots of pen items then it might be better to just go for straight HP first (banshee's and frozen mallet).

PD is an option you can consider as well against DPS, but it's kinda pricey.

In the end it'd look like:

Defensive boots
DPS item
DPS item
Another DPS item if needed, or a defensive item.
Atma's
Banshee's/Frozen Mallet

After that sell boots, buy red and green elixirs, buy boots again. Rinse and repeat when they run out.

With all that you should have decent durability. You will never be able to survive focus fire like a tank unless you give up on your DPS items, so positioning and knowing when to run and when to fight is probably more important than itemization.

Always, no excuses, vast, VAST majority of DPS must picks:

Last Whisper, Youmu's, Infinity Edge

After that written in stone, best possible three, you're looking at a choice of:

Banshee's, Guardian Angel, Bloodthirster, Exec Calling, Atma's and Phantom Dancer.

And yeah, duh, boots. Ninja, Merc, or Mobility; champion and opposition dependent.