You're likely to nab a few freebies over the course of a game by self-milling, but it's far from consistent
Because Bill is now a Supporter, you can no longer play multiple copies of that card each turn
He believes that this will have to main impacts: it will give current Standard cards more longevity and will allow mechanics and archetypes to be more effectively built on over time. Time and again, we hear that players want to play with cards they love and enjoy longer, Forsythe explained
If you have a way to also discount your red spells, Birgi helps you even generate excess mana to potentially cast your whole deck
So that makes this strong as a leader of a Mono-Black Aggro or Tokens deck that are swinging all out
For example, suppose you control Infesting Radroach, a 2/2 creature