Can someone help me counter these champions. (Come for the story, comment for the advice)

I just played against a team comp of evelyn, draven, morgana, dr. mundo, and viktor. After going 4/0 in lane as syndra I was feeling pretty confident. Then evelyn jumped on me with invis and one-shot me. And so I told myself "WHO THOUGHT THIS WAS A GOOD IDEA!?!?!" Then i tped back into the teamfight and then viktor one-shot me, the same viktor that was 0/2. And so I asked myself "WHO THOUGHT THIS WAS A GOOD IDEA!?!?!" Later in another teamfight, I was 5/2 at this point, and I got one-shot yet again by their draven, who was 2/1, and yet again I asked myself "WHO THOUGHT THIS WAS A GOOD IDEA!?!?!" Later, their mundo was solo tanking a tower, and I pounded on him repeatedly, but he took the damage and the tower, threw a cleaver that did 400+ damage and ran away, so not even for the last time, I thought to myself "WHO THOUGHT THIS WAS A GOOD IDEA!?!?!" In a different game, I was playing against a Yasuo, Kog'maw, Fizz, and some other people. So very late in the match, we three manned the Yasuo who was a bit above even, dashed through me and nearly got away, but his one q did 600+ damage, it did not crit. You can guess by now what I asked myself. Then earlier in the game, I ganked their yasuo mid lane. I was playing twitch jungle, and already had my bloodrazor. As i opened fire with ult, he jumped on my xerath, one-shot him, and ran away. You know what this sentence was going to say. Later in the game, we were taking dragon, and they hopped in and started a teamfight, I, being the jungler, was ready to make an epic play. I cracked my knuckles, I used my potions, their 0/0 fizz one-shot me. Yep. You know what I asked myself. Later in the game, I was walking down river right before my stealth and I caught sight of Kog'maw right before I stealthed. As I hopped out of stealth he killed me with 3 auto-attacks, no joke.

Can anyone please tell me how to counter these guys?