When Gray Merchant of Alphabet enters the battlefield, choose a letter. For each creature you control that has the chosen letter in its name, you gain 1 life and each opponent loses 1 life.

When Gray Merchant of Asphodel enters the battlefield, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)