I was playing with my friends, (3 of them) and I played a card from 2014, called the Gray Merchant of Asphodel. Pretty sure it is still modern. Anyways, we were confused how much life I would gain, with this as its attributes :
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.
Say I had 5 black overall ( A whole other debate)
Would I gain 5 life or 15 life?