Okay I am not sure If you have badly sorted boards (because there is the display mode which doesn't show you who responds to who, so that might've confused you) and don't see who I am responding to or you are just high (sry, just it's confusing).
I am not responding to OP's original complaint neither to Haavvik. I responded purely to this:
But, I mean. Synda can still one shot people with R despite missing all her skills, amirite?
By context, he tries to excuse both or either (unclear, he should've stated more clearly) Kog's original waveclear and/or nuke-poke of his E by Syndra's ult. He was the one brining it here and equating oneshoting champion to oneshoting wave, I just responded to that very thing. In case you have problem with these two being compared, feel absolutely free to tell that to Heartless, I agree with you on that, no need to explain that to me.
But when we have opened that:
SYNDRA Q+W to waveclear (while she needs two levels per scale)
100 / 120 / 140 / 160 / 180 Mana
12 - 8 CD
70 / 110 / 150 / 190 / 230 +75%AP
*she clears one with Q, other with W, worst case (highest damage) taken, not additive since she doesn't combine.
**note she must do this when lane is already stacked and the enemy champion has window of opportunity to make it less safe for her, she does it from 800 range of backline in order to apply both.
KOG'MAW E to waveclear
80 / 90 / 100 / 110 / 120 Mana
12 CD
60 / 105 / 150 / 195 / 240 +50%AP (+100%AP before)
*he clears reportedly entire unstacked wave on its way like this, getting less risk, from little less than 1280 range.
As for the second point. so MF's slow being more relevant is reason why those spells are comparable again?
MF E
80 Mana
14 / 13 / 12 / 11 / 10 CD
around 40 / 52 / 64 / 76 / 88 +40%AP per second twice up to
around 80 / 104 / 128 / 152 / 176 +80%AP
1000 cast-range in area (already stacked wave), smaller chance to run away when centered.
Kog slows for 20 / 28 / 36 / 44 / 52% while MF for 28 / 36 / 44 / 52 / 60%. That's just 8% difference.
And that is excluding other aspects as power budget in other abilities.