Regarding Janna/Zyra
Janna after S4 Worlds:
V5.4: Tailwind Changed to "Tailwind gives all allies in range a movement speed bonus only while they are moving toward Janna" from "Tailwind gives all allies and janna in range a movement speed bonus". Movmement speed changed to 8% from 5%. Ranged increased to 1250 from 1000 Zephyr increased to 9 / 11 / 13 / 15 / 17% from 4 / 6 / 8 / 10 / 12%.
V5.1: Howling Gale.png Howling Gale Missile width reduced to 120 from 150.
V4.19: Zephyr Cooldown increased to 12 seconds at all ranks from 12 / 11 / 10 / 9 / 8.
This is how you nerf a permapicked champ: shifting power/giving new niches/lowering numers a bit
Zyra after S3 Worlds:
V3.13:
Deadly Bloom Range reduced to 800 from 825. Damage changed to 70 / 105 / 140 / 175 / 210 (+65% AP) from 75 / 115 / 155 / 195 / 235 (+60% AP). Rampant Growth Range increased to 850 from 825. Passive cooldown reduction reduced to 2 / 4 / 6 / 8 / 10% from 4 / 8 / 12 / 16 / 20%. Plant base damage changed to 23 (+6.5 per level) from 26 (+6 per level). Reduced the delay before seeds can be stepped on by enemies to 1.5 seconds from 3. Fixed a bug where spells would rarely not turn seeds into plants. Stranglethorns No longer stuns after the knockup ends. Bug Fix: Plants summoned in the thicket will now correctly receive the buff (currently only applies to plants already active).
This is NOT how you nerf a permapicked champ: nerfing a ton of numbers all around the kit, removing 1/3 of your main CC duration, and giving a super trollish range increase on W (that means absolutely nothing), and +0.05 AP on Q (that means nearly nothing).