What first comes to mind is a couple of "reaper" cards that inflict damage and gain beneficial effects if the creature dies. There's also one that inflicts damage and gains +1/+1 when
any creature dies.
I don't think a
![Life :life](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/life18x18.png)
hunter with this ability has appeared yet, though.