Mer-Ek Nightblade — ruling 1

The cost to activate a creature’s outlast ability includes the tap symbol ({T}). A creature’s outlast ability can’t be activated unless that creature has been under your control continuously since the beginning of your turn.

Mer-Ek Nightblade — ruling 2

Several creatures with outlast also grant an ability to creatures you control with +1/+1 counters on them, including themselves. These counters could come from an outlast ability, but any +1/+1 counter on the creature will count.

Mer-Ek Nightblade : règles, fonctionnement et interactions (MTG)

Mer-Ek Nightblade is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Outlast (, : Put a +1/+1 counter on this creature. Outlast only as a sorcery.) Each creature you control with a +1/+1 counter on it has deathtouch.

How it works : Mer-Ek Nightblade

Original English text — Wizards of the Coast / Scryfall

#1September 20, 2014· Wizards of the Coast
The cost to activate a creature’s outlast ability includes the tap symbol (). A creature’s outlast ability can’t be activated unless that creature has been under your control continuously since the beginning of your turn.
No other card is named in this ruling.
#2September 20, 2014· Wizards of the Coast
Several creatures with outlast also grant an ability to creatures you control with +1/+1 counters on them, including themselves. These counters could come from an outlast ability, but any +1/+1 counter on the creature will count.
No other card is named in this ruling.