You can earn it by playing cards that allow you to take the initiative, hitting someone who has the initiative or having a player with initiative leave the game while its your turn
Today, this colorful drawing on paperboard could probably bring Sam a quick 10 grand, but hes not selling, so dont even ask
You are going to be gaining far far more value courtesy of deck design and having their guys die just means they are losing tempo and letting you snowball
We have a few Elves, like Wood Elves, to help us with ramp, Reclamation Sage, to deal with artifacts and enchantments, and Beast Whisperer, to create resources for us and draw us cards
If Grimgrin's last ability resolves, but the targeted creature isn't destroyed (perhaps because it regenerated or has indestructible), you'll still put a +1/+1 on Grimgrin
There are plenty of ways to ensure a sizable graveyard in Magic