Ok, You might think this is just a standard build. It pretty much is. Except, The Gargoyle. Trust me on this one, if you are behind in a game you must build the gargoyle at some point. (If you are not behind, streak's gauge will be more useful unless you find yourself dying too often).

So, the plan with the Gargoyle is to just charge head first into the enemy team with your adc or carries at the back.
#1 Once in range of all their damage activate Gargoyle because of the reduced 60% dmg active. (You will also have reduced damage)
#2 Because of this great perk, you will be able to get off enough hits to get a person close to maximum bleed without taking too much damage.
#3 You should still have 3/4 health by the time you have all bleed stacks on a person. So now you just go SLAMMA JAMMA BEAST MODE on their whole ****ing team because you start one shotting everybody.
#4 If you die, you should still be able to win that team fight because when you charged in, they probably used most of their abilities. So cross your fingers that your team isn't ******ed.
#5 Enemy team surrenders because I taught you the secret item to being a pentakill master.

If it goes wrong and you get cc'd the entire time and legit can't move, blame your team so you can raise your self esteem so in the next team fight you will be confident and you will dodge every skill shot. Trust me, its full proof.