I recently won a game against a Fizz. From the OP timeline:
3m: Zyra kills Fizz (first blood)
6m: Zyra kills Fizz
8m: Zyra kills Fizz
8m: Zyra dies to Shaco
11m: My team takes Cloud Drake
12m: Zyra dies to Shaco
15m: Shyv kills Fizz
15m: Zyra takes mid turret (turret fb)
16m: Fizz kills Zyra
17m: Shyv takes top turret
18m: Zyra kills Tristana
18m: Fizz kills Zyra
19m: Ezreal kills Fizz
19m: Ezreal takes bot turret
21m: Zyra kills Shaco
23m: Ezreal kills Fizz
23m: Zyra takes inner mid turret
26m: Fizz kills Zyra
29m: My team takes 5 more turrets and 3 inhibs
29m: Fizz kills Zyra
Ok, so let's look at these 100-0 kills Fizz got on me.
16m:
Fizz: (lvl 9) at 4144g. Has Protobelt, Seal, Mercs, and Refillable. Has Null Orb.
Zyra: (lvl 11) at 5445g. Has Luden's Doran's, Sorc's, and Refillable. Has Null Orb.
By the way, he missed his ult. The entire situation was so completely absurd that Fizz and I had a conversation in /all chat about it. After he got the kill, he laughed to his team about how broken it is that a 0/4 Fizz with one 2500g item can miss an ult and still nuke a mage two levels up from 100-0 with null orb.
I'll admit that Fizz is particularly hard on Zyra because his E resets plant targeting priorities. Even still, it's pretty ridiculous. And he continued to do it every couple of minutes for the rest of the game, regardless of me building hp and MR, and regardless of whether he landed his ult (which is as easy to miss as a Lux E).