Ruthless
Ruthless is R&D slang term used for “When ~ enters the battlefield, put ... -1/-1 counters on target creature you control.”
The black and green mechanic was featured in Amonkhet. In design it was actually an ability worded as Ruthless but R&D ultimately didn’t feel they had enough cards to give it an ability word.[1] It was referenced in the name of Ruthless Sniper.
There is always a second ability on the cards with Ruthless, most of the times interacting with -1/-1 counters.
Cards with Ruthless
References
- ↑ Mark Rosewater (May 06, 2017). "Why wasn't the "when ~ ETB put X -1/-1 counters on a creature you control" keyworded?". Blogatog. Tumblr.