As milling has a mental attack flavor, it is very natural in blue
Since then, the older client been rather overshadowed by Arena, whose ease of use and free to play economy has been very successful at bringing in new players
The Scorpion God also wants this because it gets you to critical mass of -1/-1 effects, which in turn makes the God a genuine card advantage engine
It is spent during spell resolution
Prison/stax decks stop your opponent from playing cards and attacking you while gaining incremental advantages over time, be it with lifegain, Treasure tokens, or card draw
It says whenever Darksteel Splicer or another nontoken Phyrexian enters the battlefield under your control, create X 3/3 colorless Phyrexian Golem artifact creature tokens, where X is the number of opponents you have