Players, in general, liked the gameplay of Omens
Or, if you are getting out under them to start, do this to set up a spot where you get to handle their things up the curve while bashing
Which means most people exile 7 cards and pay only a single blue to draw 3 cards
Death By Clues Seven mana is always expensive, but turning all your Clues into win conditions and running over your opponents is a fantastic exchange
In a world of upgraded Commander 2019 decks, I'd be looking to overload on sweepers, with the goal being to take over with Sevinne, the Chronoclasm value in the late game, but the precon seems like it will likely just get run over by faster decks while Sevinne, the Chronoclasm repeatedly dies before doing much of anything
Yes, black magic often dabbles in -X/-X effects, to represent a creature's life essence being withered away