It's not just a mana rock but also a renewable source of card draw upon sacrifice
This is made more difficult to judge because Magics story has provided absolutely no information about the story of Ravnica beyond the four story spotlight cards (Guild Summit, Assassins Trophy, Fireminds Foresight, and Thousand-Year Storm), so we Vorthoses cant point to a line of text and see why this change in character and mechanics is warranted
For sacrifice payoffs we've got drain with Blood Artist, make ramping sac fodder with Pawn of Ulamog, draw even more cards with Smothering Abomination, and exile the sacrificed creatures to return them later with Prowling Geistcatcher
(Vigilance doesnt allow a tapped creature or a creature that entered the battlefield this turn to attack, though.) ward A triggered ability that can counter spells or abilities that target the permanent with ward
Direct Damage - second to Red Anti-Enchantment - worse than White or Green Purple is between Blue and Black - enemy of Green
but do bring their own issues (they ignore the opponent's board state, mostly)
