Valtr, Master of the League

Whenever Valtr attacks, other attacking creatures get +1/+1 until end of turn for each attacking creature other than Valtr.
Whenever Valtr blocks, other blocking creatures get +1/+1 until end of turn for each blocking creature other than Valtr.

Haven't you seen enough of these wretched beasts, freakish slugs, and mad doctors? Sentence these fiends to death, with the help of your League confederates!"