Extort
Extort is a keyword introduced in Gatecrash, wherein it is the Orzhov Syndicate guild mechanic. It allows players to pay additional 
or 
for spells they cast and create a small life-draining effect.
Example
Color percentages
There is a total of 11 cards that involve extort, which divide by color as such:
- White = 36 %
- Black = 36 %
- Multicolor = 28 %