Walking Ballista is the easiest payoff creature to disrupt, as the loop cannot proceed without first resolving Heliods activated ability or some similar lifelink-granting effect
A lot of her strategies revolve around building her up with lots of equipment, and then using lots of cheap cards like Boros Charm, Temur Battle Rage, and Fight As One to buff her up more and more
Bonecrusher exceeds expectations in nearly every department
Don't worry, when I say I'll tell you everything about milling, I mean I'll start from the beginning, including what milling is
The value wise, 50 booster packs is way to go
There are only 100 cards of each version, which makes them super rare