Don't want to be the bad guy, but no matter how many games of TFT I play or whatever synergy I go, still have the same feeling.
Whenever there is some lucky guy who manage to get his dream combo 6 assasins, it's pretty much GG at that point of the game. It doesnt matter how u possition your team or what item you give them. There is always at least 1 sneaky assasin that will get to you main dps and just simply OS it. The only way to beat it is just a pure luck that that one assasin wont target your dps but instead someone else that was left behind and didn't manage to get to the front line so fast. Not gonna even talk about sorcesers. They are simply nonexistent for them. Walking throught them like an air.
Get an assasin to 3 stars, give it IE + some other crit item with 6 assasins bonus on and just watch how the enemy team falls apart. My opinion, maybe wrong but thats how I feel about it. Probably the only thing I don't like in this mode.