the tribe didnt see significant support until the original Zendikar set
The cycle was later completed in Commander Legends so all 10 color pairs have access to one
Sanguine Bond says the reverse: whenever you gain life, an opponent loses the same amount
There are, of course, weaknesses to a mill strategy some players include cards that prevent themselves from losing to an empty library, like Ulamog, the Infinite Gyre
Frank Karsten The above deck matches this up very well
It's colorless, which means it can fit into any deck, and that ping ability says what every Commander player wants to hear: you just worry about drawing cards, I'll do the winning for you