Narfi, The Aesirian Martyr

At the beginning of your upkeep, if you control a creature named Vali, Tool of Aesir Masochism, sacrifice Narfi, The Aesirian Martyr and put {x} +1/+1 counters onto
Vali, Tool of Aesir Masochism where {x} is equal to Narfi, The Aesirian Martyr's toughness.