I cannot regard this as anything but a sideboard card, but this is ridiculously out of the blue and honestly kicks the color pie right in the jimmies. It will change post board matches for sure. Ravager players are going to need to be really careful how they sac from now on.
"Killing artifact creatures and gaining life isn't a part of black's color pie!" says multiple users that aren't unaware that Sever Soul (printed in 1999) and Vraska's Contempt (printed in 2017) exist (and many others in between). It's just much more mana efficient for Vintage.
There are other, earlier examples of black creature exile as well. The earliest example I can find is (93/94-legal!) Ashes to Ashes, but there's also Eradicate, Gild, Sever the Bloodline, and Silence the Believers. (And in more recent sets, Hour of Glory and Reaver Ambush.)
To me this is out of flavor because A) it explicitly targets artifact style creatures which has not been blacks strong suit and B) it is undercosted life gain. Draining effects have typically been reserved for things that are thematically alive, which is why so many of blacks old cards could not target other black cards.
Blacks claim to fame for a long time was being able to do basically anything except deal with enchantments, and do it pretty cheaply, but with another cost associated. Compare this to other black removal spells like Vendetta.
@protoaddct Black has almost every permutation of "destroy target creature with restriction X". Destroy target nongreen creature, destroy target white or green creature, destroy target creature with CMC less than 3, destroy target monocolored creature, destroy an untapped creature, destroy a tapped creature, destroy target creature that isn't enchanted, destroy target enchanted creature, destroy target enchantment creature, destroy target spirit, destroy target non-spirit, destroy target human, destroy a non-merfolk creature, destroy a non-elf, destroy a non-elf with power =/= toughness, destroy a cleric, destroy a ninja, destroy target nonlegendary creature, destroy target legendary creature...I think I've made my point.
Destroy/exile target colorless creature was more a matter of time (and eventual need), rather than a restriction imposed by the color pie. As for gaining life, I know we focus on Eternal Formats, but R&D does not. People might think this card is designed for Modern or Vintage or Eldrazi or Shops or whatever, but that's unlikely to be true. Standard has been dominated by aggressive decks centered around Vehicles, Bomat Courier, and Scrapheap Scrounger since Kaledesh. Heck, I don't know what the timing was, but it's possible Smuggler's Copter was still unbanned then. The life gain supports this card's function as an answer to these aggro decks. Adherence to some arbitrary notion of a color wheel is likely secondary to printing functional answers to existing problems in the Standard format.