I need to know how salty/Mean this is?

6/6 flyer for 4 alone is huge, but the fact that 4 is a 6 mana discount on a really easy condition to meet for the colors it's in. On top of that +1/+1 counters are an extremely common mechanic in every color making this a once per turn arms of Hadar + spectacle-triggering lifeloss (potentially quite a lot of it) and some life gain that I think is out of color for black. Black can gain life, but it does so in drain effects, like lifelink or "opponents lose n life and you gain that much life". Here the lifegain is detached from the life loss as its own separate thing, which would make it not black but a green or white effect. Still, minor thing that last one.

I could see this kind of card being an acceptable inclusion in a modification-focused set, like the the Kamigawa one, where there is a focus on a variety of ways to get the modified status. The issue is really the cost here, something like should not get that massive discount from spectacle. Four mana is enough for one of those effects, but since we're using four colored the whole effect this thing has in once-per turn as a one-time instant or sorcery. I'd say seven mana minimum for the full card as it currently is, and that's after the spectacle discount.

Also not sure if you can call a card that 'hates' on almost every color a hate card. That's a term for something a little more targeted I think.